Biochemical components of blood in normal and pathological ...

BIOCHEMICAL COMPONENTS OF BLOOD IN NORMAL AND
PATHOLOGICAL CONDITIONS. BLOOD PROTEINS. NON-PROTEIN
NITROGENOUS CONTAINING AND NON- NITROGENOUS CONTAINING
COMPONENTS OF BLOOD.
Blood is a liquid tissue. Suspended in the watery plasma are seven types of cells
and cell fragments.
red blood cells (RBCs) or erythrocytes
platelets or thrombocytes
five kinds of white blood cells (WBCs) or leukocytes
o Three kinds of granulocytes
neutrophils
eosinophils
basophils
o Two kinds of leukocytes without granules in their cytoplasm
lymphocytes
monocytes
If one takes a sample of blood, treats it with an agent to
prevent clotting, and spins it in a centrifuge,
the red cells settle to the bottom
the white cells settle on top of them forming the
"buffy coat".
The fraction occupied by the red cells is called the
hematocrit. Normally it is approximately 45%. Values much
lower than this are a sign of anemia.

Biological functions of the blood
The blood is the most specialized fluid tissue which circulates in vascular system
and together with lymph and intercellular space compounds an internal environment of
an organism.
The blood executes such functions:
1. Transport of gases – oxygen from lungs is carried to tissues and carbon dioxide
from tissues to lungs.
2. Transport of nutrients to all cells of organism (glucose, amino acids, fatty acids,
vitamins, ketone bodies, trace substances and others). Substances such as urea, uric
acid, bilirubin and creatinine are taken away from the different organs for ultimate
excretion.
3. Regulatory or hormonal function – hormones are secreted in to blood and they
are transported by blood to their target cells.
4. Thermoregulation function - an exchange of heat between tissues and blood.
5. Osmotic function- sustains osmotic pressure in vessels.
6. Protective function- by the phagocytic action of leucocytes and by the actions of
antibodies, the blood provides the most important defense mechanism.
7. Detoxification function - neutralization of toxic substances which is connected
with their decomposition by the help of blood enzymes.
Blood performs two major functions:
transport through the body of
o oxygen and carbon dioxide
o food molecules (glucose, lipids, amino acids)
o ions (e.g., Na + , Ca 2+ , HCO3 − )
o wastes (e.g., urea)
o hormones
o heat
defense of the body against infections and other foreign materials. All the
WBCs participate in these defenses.

The formation of blood cells (cell types and acronyms are defined below)
All the various types of blood cells
human!).
are produced in the bone marrow (some 10 11 of them each day in an adult
arise from a single type of cell called a hematopoietic stem cell — an
"adult" multipotent stem cell.
These stem cells
are very rare (only about one in 10,000 bone marrow cells);
are attached (probably by adherens junctions) to osteoblasts lining the
inner surface of bone cavities;
express a cell-surface protein designated CD34;
produce, by mitosis, two kinds of progeny:

o more stem cells (A mouse that has had all its blood stem cells
killed by a lethal dose of radiation can be saved by the injection of a single
living stem cell!).
o cells that begin to differentiate along the paths leading to the
various kinds of blood cells.
Which path is taken is regulated by
the need for more of that type of blood cell which is, in turn, controlled by
appropriate cytokines and/or hormones.
Examples:
Interleukin-7 (IL-7) is the major cytokine in stimulating bone marrow
stem cells to start down the path leading to the various lymphocytes (mostly B
cells and T cells).
Erythropoietin (EPO), produced by the kidneys, enhances the production
of red blood cells (RBCs).
Thrombopoietin (TPO), assisted by Interleukin-11 (IL-11), stimulates the
production of megakaryocytes. Their fragmentation produces platelets.
Granulocyte-macrophage colony-stimulating factor (GM-CSF), as its
name suggests, sends cells down the path leading to both those cell types. In due
course, one path or the other is taken.
o Under the influence of granulocyte colony-stimulating
factor (G-CSF), they differentiate into neutrophils.
o Further stimulated by interleukin-5 (IL-5) they develop into
eosinophils.
o Interleukin-3 (IL-3) participates in the differentiation of most of the
white blood cells but plays a particularly prominent role in the formation of
basophils (responsible for some allergies).

o Stimulated by macrophage colony-stimulating factor (M-CSF) the
granulocyte/macrophage progenitor cells differentiate into monocytes,
macrophages, and dendritic cells (DCs).
Biological chemistry of blood cells
Two types of blood cells can be distinguished - white and red blood cells. White
blood cells are called leucocytes. Their quantity in adult is 4-9 x 10 9 /L.
Red blood cells are called erythrocytes. Their quantity in peripheral blood is 4,5-5
x 10 12 /L. Besides that, there are also thrombocytes or platelets in blood.
White Blood Cells (leukocytes)
Leucocytes (white blood cells) protect an organism from microorganisms, viruses
and foreign substances, that provides the immune status of an organism.
1:700),
are much less numerous than red (the ratio between the two is around
have nuclei,
participate in protecting the body from infection,
consist of lymphocytes and monocytes with relatively clear cytoplasm,
and three types of granulocytes, whose cytoplasm is filled with granules.
Leucocytes are divided into two groups: Granulocytes and agranulocytes.
Granulocytes consist of neutrophils, eosinophils and basophils. Agranulocytes consist
of monocytes and lymphocytes.
http://www.youtube.com/watch?v=8ytkFqAMoa8
http://www.youtube.com/watch?v=ce0Xndms1bc
Neutrophils

Neutrophils comprise of 60-70 % from all leucocytes. Their main function is to
protect organisms from microorganisms and viruses. Neutrophils have segmented
nucleus, endoplasmic reticulum (underdeveloped) which does not contain ribosomes,
insufficient amount of mitochondria, well-developed Golgi apparatus and hundreds of
different vesicles which contain peroxidases and hydrolases. Optimum condition for
their activity is acidic pH. There are also small vesicles which contain alkaline
phosphatases, lysozymes, lactopherins and proteins of cationic origin.
Glucose is the main source of energy for neutrophils. It is directly utilized or
converted into glycogen. 90 % of energy is formed in glycolysis, a small amount of
glucose is converted in pentosophosphate pathway. Activation of proteolysis during
phagocytosis as well as reduction of phosphatidic acid and phosphoglycerols are also
observed. The englobement is accompanied by intensifying of a glycolysis and
pentosophosphate pathway. But especially intensity of absorption of oxygen for
neutrophils - so-called flashout of respiration grows. Absorbed oxygen is spent for
formation of its fissile forms that is carried out with participation enzymes:
peroxide
1. NADP*Н -OXYDASE catalyzes formation of super oxide anion
2. An enzyme NADH- OXYDASE is responsible for formation of hydrogen
3. Мyeloperoxydase catalyzes formation of hypochloric acid from chloride and
hydrogen peroxide
Neutrophils are motile phagocyte cells that play a key role in acute inflammation.
When bacteria enter tissues, a number of phenomena occur that are collectively known
as acute inflammatory response. When neutrophils and other phagocyte cells engulf
bacteria, they exhibit a rapid increase in oxygen consumption known as the respiratory
burst. This phenomenon reflects the rapid utilization of oxygen (following a lag of 15-
60 seconds) and production from it of large amounts of reactive derivates, such as O2 - ,
H2O2, OH . and OCl - (hypochlorite ion). Some of these products are potent microbicidal
agents. The electron transport chain system responsible for the respiratory burst
contains several components, including a flavoprotein NADPH:O2-oxidoreductase
(often called NADPH-oxidase) and a b-type cytochrome.

emnants by phagocytosis.
The most abundant of the WBCs. This
photomicrograph shows a single neutrophil
surrounded by red blood cells.
Neutrophils squeeze through the capillary
walls and into infected tissue where they kill the
invaders (e.g., bacteria) and then engulf the
This is a never-ending task, even in healthy people: Our throat, nasal passages, and
colon harbor vast numbers of bacteria. Most of these are commensals, and do us no
harm. But that is because neutrophils keep them in check.
However,
heavy doses of radiation
chemotherapy
and many other forms of stress
can reduce the numbers of neutrophils so that formerly harmless bacteria begin to
proliferate. The resulting opportunistic infection can be life-threatening.
http://www.youtube.com/watch?v=EpC6G_DGqkI&feature=related
Some important enzymes and proteins of neutrophilis.
Myeloperoxidase (MPO). Catalyzed following reaction:
H2O2 + X - (halide) + H +
HOX=hypochlorous acid)
HOX + H2O (where X - = Cl - , Br - , I - or SCN - ;
HOCl, the active ingredient of household liquid bleach, is a powerful oxidant and
is highly microbicidial. When applied to normal tissues, its potential for causing
damage is diminished because it reacts with primary or secondary amines present in
neutrophils and tissues to produce various nitrogen-chlorine (N-Cl) derivates; these
chloramines are also oxidants, although less powerful than HOCl, and act as

microbicidial agents (eg, in sterilizing wounds) without causing tissue damage.
Responsible for the green color of pus.
NADPH-oxidase.
2O2 + NADPH 2O2 - + NADP + H +
Key component of the respiratory burst. Deficiency may be observed in chronic
granulomatous disease.
Lysozyme.
Hydrolyzes link between N-acetylmuramic acid and N-acetyl-D-glucosamine
found in certain bacterial cell walls. Abundant in macrophages.
Defensins.
Basic antibiotic peptides of 29-33 amino acids. Apparently kill bacteria by causing
membrane damage.
Lactoferrin.
Iron-binding protein. May inhibit growth of certain bacteria by binding iron and
may be involved in regulation of proliferation of myeloid cells.
Neutrophils contain a number of proteinases (elastase, collagenase, gelatinase,
cathepsin G, plasminogen activator) that can hydrolyze elastin, various types of
collagens, and other proteins present in the extracellular matrix. Such enzymatic action,
if allowed to proceed unopposed, can result in serious damage to tissues. Most of these
proteinases are lysosomal enzymes and exist mainly as inactive precursors in normal
neutrophils. Small amounts of these enzymes are released into normal tissues, with the
amounts increasing markedly during inflammation. The activities of elastase and other
proteinases are normally kept in check by a number of antiproteinases ( 1-
Antiproteinase, 2-Macroglobulin, Secretory leukoproteinase inhibitor, 1-
Antichymotrypsin, Plasminogen activator inhibitor-1, Tissue inhibitor of
metalloproteinase) present in plasma and the extracellular fluid.
Basophiles
Basophiles make up 1-5% of all blood leukocytes. They are actively formed in
the bone marrow during allergy. Basophiles take part in the allergic reactions, in the

lood coagulation and intravascular lipolysis. They have the protein synthesis
mechanism, which works due to the biological oxidation energy . They synthesize
the mediators of allergic reactions – histamine and serotonin, which during allergy
cause local inflammation. Heparin, which is formed in the basophiles, prevents the
blood coagulation and activates intravascular lipoprotein lipase, which splits
triacylglycerin.
The number of basophils also increases during infection. Basophils leave the blood
and accumulate at the site of infection or other inflammation. There they discharge the
contents of their granules, releasing a variety of mediators such as:
histamine
serotonin
prostaglandins and leukotrienes
which increase the blood flow to the area and in other ways add to the
inflammatory process. The mediators released by basophils also play an important part
in some allergic responses such as
hay fever and
an anaphylactic response to insect stings.
Eosinophiles
They make up 3-6% of all leukocytes. Eosinophiles as well as neutrophiles
defend the cells from microorganisms, they contain myeloperoxidase, lysosomal
hydrolases. About the relations of eosinophiles with testifies the growth of their
amount during the sensitization of organism, i.e. during bronchial asthma,
helminthiasis. They are able to pile and splits histamine, ―to dissolve‖ thrombus with
the participation of plasminogen and bradykinin-kininase.
Monocytes

They are formed in the bone marrow. They make up 4-8% of all leukocytes.
According to the function they are called macrophages. Tissue macrophages derive
from blood monocytes. Depending on their position they are called: in the liver –
reticuloendotheliocytes, in the lungs - alveolar macrophages, in the intermediate
substance of connective tissue – histocytes etc. Monocytes are characterized by a
wide set of lysosomal enzymes with the optimum activity in the acidic condition.
The major functions of monocytes and macrophages are endocytosis and
phagocytosis.
Lymphocytes
The amount – 20-25%, are formed in the lymphoid tissue or thymus, play
important role in the formation of humoral and cellular immunity. Lymphocytes have
powerful system of synthesis of antibody proteins, energy is majorily pertained due
to glycolysis, rarely – by aerobic way.
http://www.youtube.com/watch?v=cD_uAGPBfQQ&feature=related
There are several kinds of lymphocytes (although they all look alike under the
microscope), each with different functions to perform . The most common types of
lymphocytes are
B lymphocytes ("B cells"). These are responsible for making antibodies.
T lymphocytes ("T cells"). There are several subsets of these:
o inflammatory T cells that recruit macrophages and
neutrophils to the site of infection or other tissue damage
o cytotoxic T lymphocytes (CTLs) that kill virus-infected and,
perhaps, tumor cells
cells
o helper T cells that enhance the production of antibodies by B

Monocytes
continue to divide by mitosis;
Although bone marrow is the ultimate source of
lymphocytes, the lymphocytes that will become T
cells migrate from the bone marrow to the thymus
where they mature. Both B cells and T cells also take
up residence in lymph nodes, the spleen and other
tissues where they
mature into fully functional cells.
encounter antigens;
Monocytes leave the blood and become macrophages and dendritic cells.
This scanning electron micrograph (courtesy of Drs. Jan M. Orenstein and Emma
Shelton) shows a single macrophage surrounded by several lymphocytes.
Macrophages are large, phagocytic cells that engulf
foreign material (antigens) that enter the body
dead and dying cells of the body.
Thrombocytes (blood platelets)
Platelets are cell fragments produced from megakaryocytes.
Blood normally contains 150,000–350,000 per microliter (µl) or cubic millimeter
(mm 3 ). This number is normally maintained by a homeostatic (negative-feedback)
mechanism .
The amount – less than 1%, they play the main role in the process of
hemostasis. They are formed as a result of disintegration of megakaryocytes in the
bone marrow. Their –life-time is 7-9 days. In spite of the fact that thrombocytes
have no nucleus, they are able to perform practically all functions of the cell, besides
DNA synthesis.

If this value should drop much below 50,000/µl, there is a danger of uncontrolled
bleeding because of the essential role that platelets have in blood clotting.
Some causes:
certain drugs and herbal remedies;
autoimmunity.
When blood vessels are cut or damaged, the loss of blood from the system must be
stopped before shock and possible death occur. This is accomplished by solidification
of the blood, a process called coagulation or clotting.
A blood clot consists of
a plug of platelets enmeshed in a
network of insoluble fibrin molecules.
The most numerous type in the blood.
Red Blood Cells (erythrocytes)
Women average about 4.8 million of these cells per cubic millimeter (mm 3 ;
which is the same as a microliter [µl]) of blood.
Men average about 5.4 x 10 6 per µl.
These values can vary over quite a range depending on such factors as
health and altitude. (Peruvians living at 18,000 feet may have as many as 8.3 x
10 6 RBCs per µl.)
RBC precursors mature in the bone marrow closely attached to a macrophage.
They manufacture hemoglobin until it accounts for some 90% of the dry
weight of the cell.
exosomes.
The nucleus is squeezed out of the cell and is ingested by the macrophage.
No-longer-needed proteins are expelled from the cell in vesicles called

Human blood contains 25 trillion of erythrocytes.
Their main function – transportation of O2 and CO2 – they
perform due to the fact that they contain 34% of
hemoglobin, and per dry cells mass – 95%. The total
amount of hemoglobin in the blood equals 130-160 g/l. In
the process of erythropoesis the preceding cells decrease
their size. Their nuclei at the end of the process are ruined
and pushed out of the cells. 90% of glucose in the
erythrocytes is decomposed in the process of glycolysis
and 10% - by pentose-phosphate way. There are noted
congenital defects of enzymes of these metabolic ways of erythrocytes. During this
are usually observed hemolytic anemia and other structural and functional
erythrocytes’ affections.
This scanning electron micrograph (courtesy of Dr. Marion J. Barnhart) shows the
characteristic biconcave shape of red blood cells.
Thus RBCs are terminally differentiated; that is, they can never divide. They live
about 120 days and then are ingested by phagocytic cells in the liver and spleen. Most
of the iron in their hemoglobin is reclaimed for reuse. The remainder of the heme
portion of the molecule is degraded into bile pigments and excreted by the liver. Some
3 million RBCs die and are scavenged by the liver each second.
Red blood cells are responsible for the transport of oxygen and carbon dioxide.
Oxygen Transport
In adult humans the hemoglobin (Hb) molecule
consists of four polypeptides:

o two alpha (α) chains of 141 amino acids and
o two beta (β) chains of 146 amino acids
One molecule of oxygen can bind to each heme.
Each of these is attached the
prosthetic group heme.
There is one atom of iron at
the center of each heme.
http://www.youtube.com/watch?v=WXOBJEXxNEo&feature=related
The reaction is reversible.
Under the conditions of lower temperature, higher pH, and increased
oxygen pressure in the capillaries of the lungs, the reaction proceeds to the right.
The purple-red deoxygenated hemoglobin of the venous blood becomes the
bright-red oxyhemoglobin of the arterial blood.
Under the conditions of higher temperature, lower pH, and lower oxygen
pressure in the tissues, the reverse reaction is promoted and oxyhemoglobin gives
up its oxygen.
Carbon Dioxide Transport
Carbon dioxide (CO2) combines with water forming carbonic acid, which
dissociates into a hydrogen ion (H + ) and a bicarbonate ions
:
CO2 + H2O ↔ H2CO3 ↔ H + + HCO3 −
95% of the CO2 generated in the tissues is carried in the red blood cells:

It probably enters (and leaves) the cell by diffusing through transmembrane
channels in the plasma membrane. (One of the proteins that forms the channel is
the D antigen that is the most important factor in the Rh system of blood
groups.)
Once inside, about one-half of the CO2 is directly bound to hemoglobin (at
a site different from the one that binds oxygen).
The rest is converted — following the equation above — by the enzyme
carbonic anhydrase into
o bicarbonate ions that diffuse back out into the plasma and
o hydrogen ions (H + ) that bind to the protein portion of the
hemoglobin (thus having no effect on pH).
Only about 5% of the CO2 generated in the tissues dissolves directly in the plasma.
(A good thing, too: if all the CO2 we make were carried this way, the pH of the blood
would drop from its normal 7.4 to an instantly-fatal 4.5!)
When the red cells reach the lungs, these reactions are reversed and CO2 is
released to the air of the alveoli.
Anemia
Anemia is a shortage of
RBCs and/or
the amount of hemoglobin in them.
Anemia has many causes. One of the most common is an inadequate intake of iron
in the diet.
Blood Groups
Red blood cells have surface antigens that differ between people and that create
the so-called blood groups such as the ABO system and the Rh system.
An Essay on Hemoglobin Structure and Function:

Biol 175 pp. 159 (1984)
Figure 1 is a model of human deoxyhemoglobin. It was
created in RasMol version 2.6 by Roger Sayle using the pdb
coordinates from the pdb file 4hhb. The 3D coordinates
were determed from x-ray crystallography by Fermi, G.,
Perutz, M. F., Shaanan, B., Fourme, R.: The crystal structure
of human deoxyhaemoglobin at 1.74 A resolution. J Mol
Hemoglobin is the protein that carries oxygen from the lungs to the tissues and
carries carbon dioxide from the tissues back to the lungs. In order to function most
efficiently, hemoglobin needs to bind to oxygen tightly in the oxygen-rich atmosphere
of the lungs and be able to release oxygen rapidly in the relatively oxygen-poor
environment of the tissues. It does this in a most elegant and intricately coordinated
way. The story of hemoglobin is the prototype example of the relationship between
structure and function of a protein molecule.
Hemoglobin Structure
A hemoglobin molecule consists of four polypeptide chains: two alpha chains,
each with 141 amino acids and two beta chains, each with 146 amino acids. The protein
portion of each of these chains is called "globin". The a and b globin chains are very
similar in structure. In this case, a and b refer to the two types of globin. Students often
confuse this with the concept of a helix and b sheet secondary structures. But, in fact,
both the a and b globin chains contain primarily a helix secondary structure with no b
sheets.
Figure 2 is a close up view of one of the
heme groups of the human a chain from
dexoyhemoglobin. In this view, the iron is

coordinated by a histidine side chain from amino acid 87 (shown in green.)
Each a or b globin chain folds into 8 a helical segments (A-H) which, in turn, fold
to form globular tertiary structures that look roughly like sub-microscopic kidney
beans. The folded helices form a pocket that holds the working part of each chain, the
heme.
http://www.youtube.com/watch?v=eor6EK_JP40
A heme group is a flat ring molecule containing carbon, nitrogen and hydrogen
atoms, with a single Fe 2+ ion at the center. Without the iron, the ring is called a
porphyrin. In a heme molecule, the iron is held within the flat plane by four nitrogen
ligands from the porphyrin ring. The iron ion makes a fifth bond to a histidine side
chain from one of the helices that form the heme pocket. This fifth coordination bond is
to histidine 87 in the human a chain and histidine 92 in the human b chain. Both
histidine residues are part of the F helix in each globin chain. t
The Bohr Effect
The ability of hemoglobin to release oxygen, is affected by pH, CO2 and by
the differences in the oxygen-rich environment of the lungs and the oxygen-poor
environment of the tissues. The pH in the tissues is considerably lower (more
acidic) than in the lungs. Protons are generated from the reaction between carbon
dioxide and water to form bicarbonate:
CO2 + H20 -----------------> HCO3 - + H +
This increased acidity serves a twofold purpose. First, protons lower the
affinity of hemoglobin for oxygen, allowing easier release into the tissues. As all
four oxygens are released, hemoglobin binds to two protons. This helps to
maintain equilibrium towards the right side of the equation. This is known as the
Bohr effect, and is vital in the removal of carbon dioxide as waste because CO2
is insoluble in the bloodstream. The bicarbonate ion is much more soluble, and
can thereby be transported back to the lungs after being bound to hemoglobin. If

hemoglobin couldn’t absorb the excess protons, the equilibrium would shift to
the left, and carbon dioxide couldn’t be removed.
In the lungs, this effect works in the reverse direction. In the presence of the
high oxygen concentration in the lungs, the proton affinity decreases. As protons
are shed, the reaction is driven to the left, and CO2 forms as an insoluble gas to
be expelled from the lungs. The proton poor hemoglobin now has a greater
affinity for oxygen, and the cycle continues.
Haemoglobin or hemoglobin (frequently abbreviated as Hb or Hgb) is the iron-
containing oxygen-transport metalloprotein in the red blood cells of the blood in
vertebrates and other animals; in mammals the protein makes up about 97% of the red
cell’s dry content, and around 35% of the total content including water. Hemoglobin
transports oxygen from the lungs or gills to the rest of the body, such as to the muscles,
where it releases the oxygen load. Hemoglobin also has a variety of other gas-transport
and effect-modulation duties, which vary from species to species, and which in
invertebrates may be quite diverse.
The name hemoglobin is the concatenation of heme and globin, reflecting the fact
that each subunit of hemoglobin is a globular protein with an embedded heme (or
haem) group; each heme group contains an iron atom, and this is responsible for the
binding of oxygen. The most common type of hemoglobin in mammals contains four
such subunits, each with one heme group.
Mutations in the genes for the hemoglobin protein in humans result in a group of
hereditary diseases termed the hemoglobinopathies, the most common members of
which are sickle-cell disease and thalassemia. Historically in human medicine, the
hemoglobinopathy of sickle-cell disease was the first disease to be understood in its
mechanism of dysfunction, completely down to the molecular level. However, not all of
such mutations produce disease states, and are formally recognized as hemoglobin
variants (not diseases). [1][2]

Hemoglobin (Hb) is synthesized in a complex series of steps. The heme portion is
sythesized in both the the mitochondria and cytosol of the immature red blood cell,
while the globin protein portions of the molecule are sythesized by ribosomes in the
cytosol [3] . Production of Hb continues in the cell throughout its early development from
the proerythroblast to the reticulocyte in the bone marrow. At this point, the nucleus is
lost in mammals, but not in birds and many other species. Even after the loss of the
nucleus in mammals, however, residual ribosomal RNA allows further synthesis of Hb
until the reticulocyte loses its RNA soon after entering the vasculature (this
hemoglobin-synthetic RNA in fact gives the reticulocyte its reticulated appearance and
name).
The empirical chemical formula of the most common human hemoglobin is
C2952H4664N812O832S8Fe4, but as noted above, hemoglobins vary widely across species,
and even (through common mutations) slightly among subgroups of humans.
In humans, the hemoglobin molecule is an assembly of four globular protein
subunits. Each subunit is composed of a protein chain tightly associated with a non-
protein heme group. Each protein chain arranges into a set of alpha-helix structural
segments connected together in a globin fold arrangement, so called because this
arrangement is the same folding motif used in other heme/globin proteins such as
myoglobin. [4][5] This folding pattern contains a pocket which strongly binds the heme
group.
A heme group consists of an iron (Fe) atom held in a heterocyclic ring, known as a
porphyrin. The iron atom, which is the site of oxygen binding, bonds with the four
nitrogens in the center of the ring, which all lie in one plane. The iron is also bound
strongly to the globular protein via the imidazole ring of a histidine residue below the
porphyrin ring. A sixth position can reversibly bind oxygen, completing the octahedral
group of six ligands. Oxygen binds in an "end-on bent" geometry where one oxygen
atom binds Fe and the other protrudes at an angle. When oxygen is not bound, a very
weakly bonded water molecule fills the site, forming a distorted octahedron.

The iron atom may either be in the Fe 2+ or Fe 3+ state, but ferrihemoglobin
(methemoglobin) (Fe 3+ ) cannot bind oxygen. In binding, oxygen temporarily oxidizes
Fe to (Fe 3+ ), so iron must exist in the +2 oxidation state in order to bind oxygen. The
body reactivates hemoglobin found in the inactive (Fe 3+ ) state by reducing the iron
center.
In adult humans, the most common hemoglobin type is a tetramer (which contains
4 subunit proteins) called hemoglobin A, consisting of two α and two β subunits non-
covalently bound, each made of 141 and 146 amino acid residues, respectively. This is
denoted as α2β2. The subunits are structurally similar and about the same size. Each
subunit has a molecular weight of about 17,000 daltons, for a total molecular weight of
the tetramer of about 68,000 daltons. Hemoglobin A is the most intensively studied of
the hemoglobin molecules.
The four polypeptide chains are bound to each other by salt bridges, hydrogen
bonds, and hydrophobic interactions. There are two kinds of contacts between the α and
β chains: α1β1 and α1β2.
Oxyhemoglobin is formed during respiration when oxygen binds to the heme
component of the protein hemoglobin in red blood cells. This process occurs in the
pulmonary capillaries adjacent to the alveoli of the lungs. The oxygen then travels
through the blood stream to be dropped off at cells where it is utilized in aerobic
glycolysis and in the production of ATP by the process of oxidative phosphorylation. It
doesn't however help to counteract a decrease in blood pH. Ventilation, or breathing,
may reverse this condition by removal of carbon dioxide, thus causing a shift up in
pH. [6]
Deoxyhemoglobin is the form of hemoglobin without the bound oxygen. The
absorption spectra of oxyhemoglobin and deoxyhemoglobin differ. The
oxyhemoglobine has significantly lower absorption of the 660 nm wavelength than
deoxyhemoglobin, while at 940 nm its absorption is slightly higher. This difference is

used for measurement of the amount of oxygen in patient's blood by an instrument
called pulse oximeter.
Iron's oxidation state in oxyhemoglobin
The oxidation state of iron in hemoglobin is always +2. It does not change when
oxygen binds to the deoxy- form.
Assigning oxygenated hemoglobin's oxidation state is difficult because
oxyhemoglobin is diamagnetic (no net unpaired electrons), but the low-energy electron
configurations in both oxygen and iron are paramagnetic. Triplet oxygen, the lowest
energy oxygen species, has two unpaired electrons in antibonding π* molecular orbitals.
Iron(II) tends to be in a high-spin configuration where unpaired electrons exist in eg
antibonding orbitals. Iron(III) has an odd number of electrons and necessarily has

unpaired electrons. All of these molecules are paramagnetic (have unpaired electrons),
not diamagnetic, so an unintuitive distribution of electrons must exist to induce
diamagnetism.
The three logical possibilities are:
1) Low-spin Fe 2+ binds to high-energy singlet oxygen. Both low-spin iron and
singlet oxygen are diamagnetic.
2) High-spin Fe 3+ binds to .O2 - (the superoxide ion) and antiferromagnetism
oppositely aligns the two unpaired electrons, giving diamagnetic properties.
3) Low-spin Fe 4+ binds to O2 2- . Both are diamagnetic.
X-ray photoelectron spectroscopy suggests that iron has an oxidation state of
approximately 3.2 and infrared stretching frequencies of the O-O bond suggests a bond
length fitting with superoxide. The correct oxidation state of iron is thus the +3 state
with oxygen in the -1 state. The diamagnetism in this configuration arises from the
unpaired electron on superoxide aligning antiferromagnetically in the opposite direction
from the unpaired electron on iron. The second choice being correct is not surprising
because singlet oxygen and large separations of charge are both unfavorably high-
energy states. Iron's shift to a higher oxidation state decreases the atom's size and
allows it into the plane of the porphyrin ring, pulling on the coordinated histidine
residue and initiating the allosteric changes seen in the globulins. The assignment of
oxidation state, however, is only a formalism so all three models may contribute to
some small degree.
Early postulates by bioinorganic chemists claimed that possibility (1) (above) was
correct and that iron should exist in oxidation state II (indeed iron oxidation state III as
methemoglobin, when not accompanied by superoxide .O2 - to "hold" the oxidation
electron, is incapable of binding O2). The iron chemistry in this model was elegant, but
the presence of singlet oxygen was never explained. It was argued that the binding of an
oxygen molecule placed high-spin iron(II) in an octahedral field of strong-field ligands;

this change in field would increase the crystal field splitting energy, causing iron's
electrons to pair into the diamagnetic low-spin configuration.
Binding of ligands
Binding and release of ligands induces a conformational (structural) change in
hemoglobin. Here, the binding and release of oxygen illustrates the structural
differences between oxy- and deoxyhemoglobin, respectively. Only one of the four
heme groups is shown.
As discussed above, when oxygen binds to the iron center it causes contraction of
the iron atom, and causes it to move back into the center of the porphyrin ring plane
(see moving diagram). At the same time, the porphyrin ring plane itself is pushed away
from the oxygen and toward the imidizole side chain of the histidine residue interacting
at the other pole of the iron. The interaction here forces the ring plane sideways toward
the outside of the tetramer, and also induces a strain on the protein helix containing the
histidine, as it moves nearer the iron. This causes a tug on this peptide strand which
tends to open up heme units in the remainder of the molecule, so that there is more
room for oxygen to bind at their heme sites.
In the tetrameric form of normal adult hemoglobin, the binding of oxygen is thus a
cooperative process. The binding affinity of hemoglobin for oxygen is increased by the
oxygen saturation of the molecule, with the first oxygens bound influencing the shape

of the binding sites for the next oxygens, in a way favorable for binding. This positive
cooperative binding is achieved through steric conformational changes of the
hemoglobin protein complex as discussed above, i.e. when one subunit protein in
hemoglobin becomes oxygenated, this induces a conformational or structural change in
the whole complex, causing the other subunits to gain an increased affinity for oxygen.
As a consequence, the oxygen binding curve of hemoglobin is sigmoidal, or S-shaped,
as opposed to the normal hyperbolic curve associated with noncooperative binding.
Hemoglobin's oxygen-binding capacity is decreased in the presence of carbon
monoxide because both gases compete for the same binding sites on hemoglobin,
carbon monoxide binding preferentially in place of oxygen. Carbon dioxide occupies a
different binding site on the hemoglobin. Through the enzyme carbonic anhydrase,
carbon dioxide reacts with water to give carbonic acid, which decomposes into
bicarbonate and protons:
CO2 + H2O → H2CO3 → HCO3 - + H +
The sigmoidal shape of hemoglobin's oxygen-dissociation curve results from
cooperative binding of oxygen to hemoglobin.
Hence blood with high carbon dioxide levels is also lower in pH (more acidic).
Hemoglobin can bind protons and carbon dioxide which causes a conformational
change in the protein and facilitates the release of oxygen. Protons bind at various

places along the protein, and carbon dioxide binds at the alpha-amino group forming
carbamate. Conversely, when the carbon dioxide levels in the blood decrease (i.e., in
the lung capillaries), carbon dioxide and protons are released from hemoglobin,
increasing the oxygen affinity of the protein. This control of hemoglobin's affinity for
oxygen by the binding and release of carbon dioxide and acid, is known as the Bohr
effect.
The binding of oxygen is affected by molecules such as carbon monoxide (CO)
(for example from tobacco smoking, cars and furnaces). CO competes with oxygen at
the heme binding site. Hemoglobin binding affinity for CO is 200 times greater than its
affinity for oxygen, meaning that small amounts of CO dramatically reduces
hemoglobin's ability to transport oxygen. When hemoglobin combines with CO, it
forms a very bright red compound called carboxyhemoglobin. When inspired air
contains CO levels as low as 0.02%, headache and nausea occur; if the CO
concentration is increased to 0.1%, unconsciousness will follow. In heavy smokers, up
to 20% of the oxygen-active sites can be blocked by CO.
In similar fashion, hemoglobin also has competitive binding affinity for cyanide
(CN - ), sulfur monoxide (SO), nitrogen dioxide (NO2), and sulfide (S 2- ), including
hydrogen sulfide (H2S). All of these bind to iron in heme without changing its oxidation
state, but they nevertheless inhibit oxygen-binding, causing grave toxicity.
The iron atom in the heme group must be in the Fe 2+ oxidation state to support
oxygen and other gases' binding and transport. Oxidation to Fe 3+ state converts
hemoglobin into hemiglobin or methemoglobin (pronounced "MET-hemoglobin"),
which cannot bind oxygen. Hemoglobin in normal red blood cells is protected by a
reduction system to keep this from happening. Nitrogen dioxide and nitrous oxide are
capable of converting a small fraction of hemoglobin to methemoglobin, however this
is not usually of medical importance (nitrogen dioxide is poisonous by other
mechanisms, and nitrous oxide is routinely used in surgical anesthesia in most people
without undue methemoglobin buildup).

In people acclimated to high altitudes, the concentration of 2,3-
bisphosphoglycerate (2,3-BPG) in the blood is increased, which allows these
individuals to deliver a larger amount of oxygen to tissues under conditions of lower
oxygen tension. This phenomenon, where molecule Y affects the binding of molecule X
to a transport molecule Z, is called a heterotropic allosteric effect.
A variant hemoglobin, called fetal hemoglobin (HbF, α2γ2), is found in the
developing fetus, and binds oxygen with greater affinity than adult hemoglobin. This
means that the oxygen binding curve for fetal hemoglobin is left-shifted (i.e., a higher
percentage of hemoglobin has oxygen bound to it at lower oxygen tension), in
comparison to that of adult hemoglobin. As a result, fetal blood in the placenta is able
to take oxygen from maternal blood.
Hemoglobin also carries nitric oxide in the globin part of the molecule. This
improves oxygen delivery in the periphery and contributes to the control of respiration.
NO binds reversibly to a specific cystein residue in globin; the binding depends on the
state (R or T) of the hemoglobin. The resulting S-nitrosylated hemoglobin influences
various NO-related activities such as the control of vascular resistance, blood pressure
and respiration. NO is released not in the cytoplasm of erythrocytes but is transported
by an anion exchanger called AE1 out of them. [7]
Degradation of hemoglobin in vertebrate animals
When red cells reach the end of their life due to aging or defects, they are broken
down, the hemoglobin molecule is broken up and the iron gets recycled. When the
porphyrin ring is broken up, the fragments are normally secreted in the bile by the liver.
This process also produces one molecule of carbon monoxide for every molecule of
heme degraded [4]; this is one of the few natural sources of carbon monoxide
production in the human body, and is responsible for the normal blood levels of carbon
monoxide even in people breathing pure air. The other major final product of heme
degradation is bilirubin. Increased levels of this chemical are detected in the blood if
red cells are being destroyed more rapidly than usual. Improperly degraded hemoglobin

protein or hemoglobin that has been released from the blood cells too rapidly can clog
small blood vessels, especially the delicate blood filtering vessels of the kidneys,
causing kidney damage
Role in disease
Decrease of hemoglobin, with or without an absolute decrease of red blood cells,
leads to symptoms of anemia. Anemia has many different causes, although iron
deficiency and its resultant iron deficiency anemia are the most common causes in the
Western world. As absence of iron decreases heme synthesis, red blood cells in iron
deficiency anemia are hypochromic (lacking the red hemoglobin pigment) and
microcytic (smaller than normal). Other anemias are rarer. In hemolysis (accelerated
breakdown of red blood cells), associated jaundice is caused by the hemoglobin
metabolite bilirubin, and the circulating hemoglobin can cause renal failure.
Some mutations in the globin chain are associated with the hemoglobinopathies,
such as sickle-cell disease and thalassemia. Other mutations, as discussed at the
beginning of the article, are benign and are referred to merely as hemoglobin variants.
There is a group of genetic disorders, known as the porphyrias that are
characterized by errors in metabolic pathways of heme synthesis. King George III of the
United Kingdom was probably the most famous porphyria sufferer.
To a small extent, hemoglobin A slowly combines with glucose at a certain
location in the molecule. The resulting molecule is often referred to as Hb A1c. As the
concentration of glucose in the blood increases, the percentage of Hb A that turns into
Hb A1c increases. In diabetics whose glucose usually runs high, the percent Hb A1c also
runs high. Because of the slow rate of Hb A combination with glucose, the Hb A1c
percentage is representative of glucose level in the blood averaged over a longer time
(the half-life of red blood cells, which is typically 50-55 days).

Diagnostic use
Hemoglobin levels are amongst the most commonly performed blood tests, usually
as part of a full blood count or complete blood count. Results are reported in g/L, g/dL
or mol/L. For conversion, 1 g/dL is 0.621 mmol/L. If the total hemoglobin
concentration in the blood falls below a set point, this is called anemia. Normal values
for hemoglobin levels are:
15.1 g/dl
g/dl
g/dl
11 to 12 g/dl [5]
Women: 12.1 to
Men: 13.8 to 17.2
Children: 11 to 16
Pregnant women:
Anemias are further subclassified by the size of the red blood cells, which are the
cells which contain hemoglobin in vertebrates. They can be classified as microcytic
(small sized red blood cells), normocytic (normal sized red blood cells), or macrocytic
(large sized red blood cells). The hemaglobin is the typical test used for blood donation.
A comparison with the hematocrit can be made by multiplying the hemaglobin by three.
For example, if the hemaglobin is measured at 17, that compares with a hematocrit of
.51.[6]
Glucose levels in blood can vary widely each hour, so one or only a few samples
from a patient analyzed for glucose may not be representative of glucose control in the
long run. For this reason a blood sample may be analyzed for Hb A1c level, which is
more representative of glucose control averaged over a longer time period (determined
by the half-life of the individual's red blood cells, which is typically 50-55 days).
People whose Hb A1c runs 6.0% or less show good longer-term glucose control. Hb A1c

values which are more than 7.0% are elevated. This
test is especially useful for diabetics. [8]
Lymphocytes
There are several kinds of lymphocytes
(although they all look alike under the microscope),
each with different functions to perform . The most
common types of lymphocytes are
B lymphocytes ("B cells"). These are responsible for making antibodies.
T lymphocytes ("T cells"). There are several subsets of these:
o inflammatory T cells that recruit macrophages and
neutrophils to the site of infection or other tissue damage
o cytotoxic T lymphocytes (CTLs) that kill virus-infected and,
perhaps, tumor cells
cells
o helper T cells that enhance the production of antibodies by B
Although bone marrow is the ultimate source of lymphocytes, the lymphocytes
that will become T cells migrate from the bone marrow to the thymus where they
mature. Both B cells and T cells also take up residence in lymph nodes, the spleen and
other tissues where they
Monocytes
encounter antigens;
continue to divide by mitosis;
mature into fully functional cells.
Monocytes leave the blood and become macrophages and dendritic cells.

This scanning electron micrograph (courtesy of Drs. Jan M. Orenstein and Emma
Shelton) shows a single macrophage surrounded by several lymphocytes.
Macrophages are large, phagocytic cells that engulf
Platelets
foreign material (antigens) that enter the body
dead and dying cells of the body.
Platelets are cell fragments produced from megakaryocytes.
Blood normally contains 150,000–350,000 per microliter (µl) or cubic millimeter
(mm 3 ). This number is normally maintained by a homeostatic (negative-feedback)
mechanism .
If this value should drop much below 50,000/µl, there is a danger of uncontrolled
bleeding because of the essential role that platelets have in blood clotting.
Some causes:
certain drugs and herbal remedies;
autoimmunity.
When blood vessels are cut or damaged, the loss of blood from the system must be
stopped before shock and possible death occur. This is accomplished by solidification
of the blood, a process called coagulation or clotting.
A blood clot consists of
Plasma
a plug of platelets enmeshed in a
network of insoluble fibrin molecules.
Plasma is the straw-colored liquid in which the blood cells are suspended.

sugar)
Composition of blood
plasma
Component
Water
Proteins
Pe
rcent
2
8
~9
6–
Salts 0.8
Lipids 0.6
Glucose (blood
0.1
Plasma transports materials needed by cells and materials that must be removed
from cells:
various ions (Na + , Ca 2+ , HCO3 − , etc.
glucose and traces of other sugars
amino acids
other organic acids
cholesterol and other lipids
hormones
urea and other wastes
Most of these materials are in transit from a place where they are added to the
blood (a "source")
exchange organs like the intestine
depots of materials like the liver
to places ("sinks") where they will be removed from the blood.

every cell
exchange organs like the kidney, and skin.
Serum Proteins
Proteins make up 6–8% of the blood. They are
about equally divided between serum albumin and a great
variety of serum globulins.
After blood is withdrawn from a vein and
allowed to clot, the clot slowly shrinks. As it does so, a clear fluid called serum is
squeezed out. Thus:
Serum is blood plasma without fibrinogen and other clotting factors.
The serum proteins can be separated by electrophoresis.
A drop of serum is applied in a band to a thin sheet of supporting material,
like paper, that has been soaked in a slightly-alkaline salt solution.
At pH 8.6, which is commonly used, all the proteins are negatively
charged, but some more strongly than others.
A direct current can flow through the paper because of the conductivity of
the buffer with which it is moistened.
electrode.
As the current flows, the serum proteins move toward the positive
The stronger the negative charge on a protein, the faster it migrates.
After a time (typically 20 min), the current is turned off and the proteins
stained to make them visible (most are otherwise colorless).
The separated proteins appear as distinct bands.
The most prominent of these and the one that moves closest to the positive
electrode is serum albumin.

Serum albumin
o is made in the liver
o binds many small molecules for transport through the blood
o helps maintain the osmotic pressure of the blood
The other proteins are the various serum globulins.
They migrate in the order
o alpha globulins (e.g., the proteins that transport thyroxine and
retinol [vitamin A])
o beta globulins (e.g., the iron-transporting protein transferrin)
o gamma globulins.
Gamma globulins are the least negatively-charged serum
proteins. (They are so weakly charged, in fact, that some are swept in the
flow of buffer back toward the negative electrode.)
Most antibodies are gamma globulins.
Therefore gamma globulins become more abundant following
infections or immunizations.
Albumins – multidispersed fraction of blood plasma which are characterized by
the high electrophoretic mobility and mild dissolubility in water and saline solutions.
Molecular weight of albumins is about 60000. Due to high hydrophilic properties
albumins bind a significant amount of water, and the volume of their molecule under
hydratation is doubled. Hydrative layer formed around the serum albumins provides to
70-80 % of oncotic pressure of blood plasma proteins, that can be applied in clinical
practice at albumins transfusion to patients with tissue edemas. The decreasing of
albumins concentration in blood plasma, for example under disturbance of their
synthesis in hepatocytes at liver failure, can cause the water transition from a vessels
into the tissues and development of oncotic edemas.
Albumins execute also important physiological function as transporters of a lot of
metabolites and diverse low molecular weight structures. The molecules of albumins

have several sites with centers of linkage for molecules of organic ligands, which are
affixed by the electrostatic and hydrophobic bonds. Serum albumins can affix and
convey fatty acids, cholesterol, cholic pigments (bilirubin and that similar), vitamins,
hormones, some amino acids, toxins and medicines.
Albumins also execute the buffer function. Due to the availability in their structure
amino and carboxylic groups albumins can react both as acids and as alkaline.
Albumins can bound different toxins in blood plasma (bilirubin, foreign
substances et c.). This is the desintoxicative function of albumins.
Albumins also play role of amino acids depot in the organism. They can supply
amino acids for the building of another proteins, for example enzymes.
Globulins - heterogeneous fraction of blood proteins which execute transport ( 1-
globulins – transport of lipids, thyroxin, corticosteroid hormones; 2-globulins -
transport of lipids, copper ions; -globulins - transport of lipids, iron) and protective
(participation of -globulins in immune reactions as antitoxins; -globulins as
immunoglobulins) functions. They also support the blood oncotic pressure and acid-
alkaline balance, provide amino acids for the organism requirements. The molecular
weight of globulins is approximately 150000-300000.
The globulin level in blood plasma is 20-40 g/l. A ratio between concentrations of
albumins and globulins (so called ―protein coefficient‖) in blood plasma is often
determined in clinical practice. In healthy people this coefficient is 1,5-2,0.
Fibrinogen – important protein of blood plasma, precursor of fibrin, the structural
element of blood clots. Fibrinogen participates in blood clotting and thus prevents the
loss of blood from the vascular system of vertebrates. The approximate molecular
weight of fibrinogen is 340000. It is the complex protein, it contains the carbohydrate
as prosthetic group. The content of firinogen in blood is 3-4 g/l.
Subfractions of 1, 2, and globulins, their structure and functions.
Immunoglobulins (Ig A, Ig G, Ig E, Ig M) - proteins of -globulin fraction of
blood plasma executing the functions of antibodies which are the main effectors of
humoral immunity. They appear in the blood serum and certain cells of a vertebrate in

esponse to the introduction of a protein or some other macromolecule foreign to that
species.
Immunoglobulin molecules have bindind sites that are specific for and
complementary to the structural features of the antigen that induced their formation.
Antibodies are highly specific for the foreign proteins that evoke their formation.
Molecules of immunoglobulins are glycoproteins. The protein part of
immunoglobulins contain four polipeptide chains: two heavy H-chains and two light L-
chains.
C-reactive protein ( -fraction). This protein received the title owing to its capacity
to react with C-polysaccharide of a pneumococcus forming precipitates. According to
its chemical nature C-reactive protein is glycoprotein.
In blood plasma of healthy people the C-reactive protein is absent but it occurs at
pathological states accompanied by an inflammation and necrosis of tissues. The
availability of C-reactive protein is characteristic for the acute period of diseases –
―protein of an acute phase‖. The determination of C-reactive protein has diagnostic
value in an acute phase of rheumatic disease, at a myocardial infarction, pneumococcal,
streptococcal, staphylococcal infections.
Crioglobulin - the protein of the -globulin fraction. Like to the C-reactive protein
crioglobulin absent in blood plasma of the healthy people and occurs at leukoses,
rheumatic disease, liver cirrhosis, nephroses. The characteristic physico-chemical
feature of crioglobulin is its dissolubility at standard body temperature (37 o C) and
capacity to form the sediment at cooling of a blood plasma up to 4 o C.
2-macroglobulin - protein of 2-globulin fraction, universal serum proteinase
inhibitor. Its contents (2,5 g/l) in blood plasma is highest comparing to another
proteinase inhibitors.
The biological role of 2-macroglobulin consists in regulation of the tissue
proteolysis systems which are very important in such physiological and pathological
processes as blood clotting, fibrinolysis, processes of immunodefence, functionality of a
complement system, inflammation, regulation of vascular tone (kinine and renin-
angiothensine system).

1-antitrypsin ( 1-globulin) – glycoprotein with a molecular weight 55 kDa. Its
concentration in blood plasma is 2-3 г/л. The main biological property of this inhibitor
is its capacity to form complexes with proteinases oppressing proteolitic activity of
such enzymes as trypsin, chemotrypsin, plasmin, trombin. The content of 1-antitrypsin
is markedly increased in inflammatory processes. The inhibitory activity of 1-
antitrypsin is very important in pancreas necrosis and acute pancreatitis because in these
conditions the proteinase level in blood and tissues is sharply increased. The congenital
deficiency of 1-antitrypsin results in the lung emphysema.
Fibronectin – glycoprotein of blood plasma that is synthesized and secreted in
intercellular space by different cells. Fibronectin present on a surface of cells, on the
basal membranes, in connective tissue and in blood. Fibronectin has properties of a
«sticking» protein and contacts with the carbohydrate groups of gangliosides on a
surface of plasma membranes executing the integrative function in intercellular
interplay. Fibronectin also plays important role in the formation of the pericellular
matrix.
Haptoglobin - protein of 2-globulin fraction of blood plasma. Haptoglobin has
capacity to bind a free haemoglobin forming a complex that refer to -globulins
electrophoretic fraction. Normal concentration in blood plasma - 0,10-0,35 g/l.
Haptoglobin-hemoglobin complexes are absorbed by the cells of reticulo-
endothelial system, in particular in a liver, and oxidized to cholic pigments. Such
haptoglobin function promotes the preservation of iron ions in an organism under
conditions of a physiological and pathological erythrocytolysis.
Transferrin - glycoprotein belonging to the -globulin fraction. It binds in a blood
plasma iron ions (Fe 3+ ). The protein has on the surface two centers of linkage of iron.
Transferrin is a transport form of iron delivering its to places of accumulation and
usage.
Ceruloplasmin - glycoprotein of the 2-globulin fraction. It can bind the copper
ions in blood plasma. Up to 3 % of all copper contents in an organism and more than 90
% copper contents in plasma is included in ceruloplasmin. Ceruloplasmin has properties
of ferroxidase oxidizing the iron ions. The decrease of ceruloplasmin in organism

(Wilson disease) results in exit of copper ions from vessels and its accumulation in the
connective tissue that shows by pathological changes in a liver, main brain, cornea.
The place of synthesis of each fraction and subfruction of blood plasma proteins.
Albumins, 1-globulins, fibrinogen are fully synthesized in hepatocytes.
Immunoglobulins are produced by plasmocytes (immune cells). In liver cryoglobulins
and some other -globulins are produced too. 2-globulins and -globulins are partly
synthesized in liver and partly in reticuloendothelial cells.
Causes and consequences of protein content changes in blood plasma.
Hypoproteinemia - decrease of the total contents of proteins in blood plasma. This
state occurs in old people as well as in pathological states accompanying with the
oppressing of protein synthesis (liver diseases) and activation of decomposition of
tissue proteins (starvation, hard infectious diseases, state after hard trauma and
operations, cancer). Hypoproteinemia (hypoalbuminemia) also occurs in kidney
diseases, when the increased excretion of proteins via the urine takes place.
Hyperproteinemia - increase of the total contents of proteins in blood plasma.
There are two types of hyperproteinemia - absolute and relative.
Absolute hyperproteinemia – accumulation of the proteins in blood. It occurs in
infection and inflammatory diseases (hyperproduction of immunoglobulins), rheumatic
diseases (hyperproduction of C-reactive protein), some malignant tumors (myeloma)
and others.
Relative hyperproteinemia – the increase of the protein concentration but not the
absolute amount of proteins. It occurs when organism loses water (diarrhea, vomiting,
fever, intensive physical activity etc.).
The principle of the measurement of protein fractions by electrophoresis method.
Electrophoresis is the separation of proteins on the basis of their electric charge. It
depends ultimately on their base-acid properties, which are largely determined by the
number and types of ionizable R groups in their polipeptide chains. Since proteins
differ in amino acid composition and sequence, each protein has distinctive acid-base
properties. There are a number of different forms of electroforesis useful for analyzing
and separating mixtures of proteins

If a precursor of an antibody-secreting
cell becomes cancerous, it divides
uncontrollably to generate a clone of
plasma cells secreting a single kind of antibody molecule. The image
(courtesy of Beckman Instruments, Inc.) shows — from left to right —
the electrophoretic separation of:
globulins;
1. normal human serum with its diffuse band of gamma
2. serum from a patient with multiple myeloma producing an
IgG myeloma protein;
3. serum from a patient with Waldenström's macroglobulinemia
where the cancerous clone secretes an IgM antibody;
4. serum with an IgA myeloma protein.
Gamma globulins can be harvested from donated blood (usually
pooled from several thousand donors) and injected into persons exposed to
certain diseases such as chicken pox and hepatitis. Because such preparations of
immune globulin contain antibodies against most common infectious diseases,
the patient gains temporary protection against the disease.
Serum Lipids
Because of their relationship to cardiovascular disease, the analysis of serum lipids
has become an important health measure.
The table shows the range of typical values as well as the values above (or below)
which the subject may be at increased risk of developing atherosclerosis.
LIPID
Typical values
(mg/dl)
Desirable
(mg/dl)

(total)
Cholesterol
LDL
cholesterol
HDL
cholesterol
s
Triglyceride
170–210

agar gel.
B. Protein fractions which are received with the help of imunoelectropheresis on
Protein Concentration
Acidic α1
glycoproteid
(Ig)
Fractions Concentration Relative contents
Albumin 38,0 - 50,0 g/l 0,50 - 0,60
α1 globulins 1,4 – 3,0 g/l 0,01 - 0,05
α2 globulins 5,6 – 9,1 g/l 0,07 - 0,13
β- globulins 5,4 – 9,1 g/l 0,09 – 0,15
γ globulins 9,1 – 14,7 g/l 0,14 – 0,22
Total protein 65,0 – 85, 0 g/l 1,00
α1Antitrypsyn
Ceruloplasmin
Cu 2+
Haptoglobine
α2 - Macroglobulin
Transpheryn
Fe 3+
Fibrinogen
Immunoglobulins
IgG
IgA
IgM
IgD
IgE
16,0-31,0
mkmmol/l
11,0-27,0
mkmmol/l
0,20 – 0,40 g/l
2,00-4,00 g/l
0,15-0,60 g/l
1,00-4,00 g/l
2,50-3,50 g/l
2,50-4,10 g/l
2,00-4,00 g/l
8,00-18,00 g/l
1,00-4,00 g/l
0,60-2,80 g/l
0,00-0,15 g/l
Till 5x10 -4

Residual nitrogen, its components, ways of their formation, blood
content
The state of protein nutrition can be determined by measuring the dietary intake
and output of nitrogenous compounds from the body. Although nucleic acids also
contain nitrogen, protein is the major dietary source of nitrogen and measurement of
total nitrogen intake gives a good estimate of protein intake (mg N Ч 6.25 = mg protein,
as nitrogen is 16% of most proteins). The output of nitrogen from the body is mainly in
urea and smaller quantities of other compounds in urine and undigested protein in feces,
and significant amounts may also be lost in sweat and shed skin.
The difference between intake and output of nitrogenous compounds is known as
nitrogen balance. Three states can be defined: In a healthy adult, nitrogen balance is in
equilibrium when intake equals output, and there is no change in the total body content
of protein. In a growing child, a pregnant woman, or in recovery from protein loss, the
excretion of nitrogenous compounds is less than the dietary intake and there is net
retention of nitrogen in the body as protein, ie, positive nitrogen balance. In response
to trauma or infection or if the intake of protein is inadequate to meet requirements
there is net loss of protein nitrogen from the body, ie, negative nitrogen balance. The
continual catabolism of tissue proteins creates the requirement for dietary protein even
in an adult who is not growing, though some of the amino acids released can be
reutilized.
Nitrogen balance studies show that the average daily requirement is 0.6 g of
protein per kilogram of body weight (the factor 0.75 should be used to allow for
individual variation), or approximately 50 g/d. Average intakes of protein in developed
countries are about 80–100 g/d, ie, 14–15% of energy intake. Because growing children
are increasing the protein in the body, they have a proportionately greater requirement
than adults and should be in positive nitrogen balance. Even so, the need is relatively

small compared with the requirement for protein turnover. In some countries, protein
intake may be inadequate to meet these requirements, resulting in stunting of growth.
Residual nitrogen – nonprotein nitrogen, that is nitrogen of organic and
inorganic compounds that remain in blood after protein sedimentation.
Organic and inorganic compounds of residual nitrogen are as follows: urea (50 %
of the residual nitrogen), amino acids (25 %), creatine and creatinine (7,5 %), salts of
ammonia and indicane (0,5 %), other compounds (about 13 %).
Urea is formed in liver during the degradation of amino acids, pyrimidine
nucleotides and other nitrogen containing compounds. Amino acids are formed as result
of protein decomposition or owing to the conversion of fatty acids or carbohydrates to
amino acids. The pool of amino acids in blood is also supported by the process of their
absorption in intestine. Creatine is produced in kidneys and liver from amino acids
glycine and arginine, creatinine is formed in muscles as result of creatine phosphate
splitting. In result of ammonia neutralization the ammonia salts can be formed. Indicane
is the product of indol neutralization in the liver.

Creatinine Urine
The content of residual nitrogen in blood is 0,2 – 0,4 g/l.
The pathways of convertion of amino acid nonnitrogen residues.
The removal of the amino group of an amino acid by transamination or
oxidative deamination produces an α-keto acid that contains the carbon skeleton
from the amino acid (nonnitrogen residues). These α-keto acids can be used for the
biosynthesis of non-essential amino acids or undergoes a different degradation
process. For alanine and serine, the degradation requires a single step. For most
carbon arrangements, however, multistep reaction sequences are required. There

are only seven degradation sequences for 20 amino acids. The seven degradation
products are pyruvate, acetyl CoA, acetoacetyl CoA, α-ketoglutarate, succinyl
CoA, fumarate, and oxaloacetate. The last four products are intermediates in the
citric acid cycle. Some amino acids have more than one pathway for degradation.
The major point of entry into the tricarboxylate cycle is via acetyl-CoA; 10 amino
acids enter by this route. Of these, six (alanine, glycine, serine, threonine, tryptophan
and cysteine) are degraded to acetyl-CoA via pyruvate, five (phenylalanine, tyrosine,
leucine, lysine, and tryptophan) are degraded via acetoacetyl-CoA, and three
(isoleucine, leucine and tryptophan) yield acetyl-CoA directly. Leucine and tryptophan
yield both acetoacetyl-CoA and acetyl-CoA as end products.
The carbon skeletons of five amino acids (arginine, histidine, glutamate, glutamine
and proline) enter the tricarboxylic acid cycle via -ketoglutarate.
The carbon skeletons of methionine, isoleucine, and valine are ultimately degraded
via propionyl-CoA and methyl-malonyl-CoA to succinyl-CoA; these amino acids are
thus glycogenic.
Fumarate is formed in catabolism of phenylalanine, aspartate and tyrosine.
Oxaloacetate is formed in catabolism of aspartate and asparagine. Aspartate is
converted to the oxaloacetate by transamination.
Amino acids that are degraded to citric acid cycle intermediates can serve as
glucose precursors and are called glucogenic. A glucogenic amino acid is an amino
acid whose carbon-containing degradation product(s) can be used to produce glucose
via gluconeogenesis.
Amino acids that are degraded to acetyl CoA or acetoacetyl CoA can
contribute to the formation of fatty acids or ketone bodies and are called
ketogenic. A ketogenic amino acid is an amino acid whose carbon-containing
degradation product(s) can be used to produce ketone bodies.
Amino acids that are degraded to pyruvate can be either glucogenic or ketogenic.
Pyruvate can be metabolized to either oxaloacetate (glucogenic) or acetyl CoA
(ketogenic).

Only two amino acids are purely ketogenic: leucine and lysine. Nine amino acids
are both glucogenic and ketogenic: those degraded to pyruvate (alanine, glycine,
cysteine, serine, threonine, tryptophan), as well as tyrosine, phenylalanine, and
isoleucine (which have two degradation products). The remaining nine amino acids are
purely glucogenic (arginine, asparagine, aspartate, glutamine, glutamate, valine,
histidine, methionine, proline)
The regulation of protein metabolism. Protein metabolism is regulated by different
hormones. All hormones according to their action on protein synthesis or splitting are
divided on two groups: anabolic and catabolic. Anabolic hormones promote to the
protein synthesis. Catabolic hormones enhance the decomposition of proteins.
Somatotropic hormone (STH, growth hormone):
- stimulates the passing of amino acids into the cells;
- activates the synthesis of proteins, DNA, RNA.
Thyroxine and triiodthyronine:
- in normal concentration stimulate the synthesis of proteins and
nucleic acids;
Insulin:
Glucagon:
Epinephrine:
- in excessive concentration activate the catabolic processes.
- increases the permeability of cell membranes for amino acids;
- activates synthesis of proteins and nucleic acids;
- inhibits the conversion of amino acids into carbohydrates.
- stimulates the conversion of amino acids into carbohydrates.
- activates the protein decomposition.
Glucocorticoids:
- stimulate the catabolic processes (protein decomposition) in
connective, lymphoid and muscle tissues and activate the processes of protein
synthesis in liver;
- stimulate the activity of aminotransferases;

azotemia.
Sex hormones:
- activate the synthesis of urea.
- stimulate the processes of protein, DNA, RNA synthesis;
- cause the positive nitrogenous balance.
The role of liver in protein metabolism:
– synthesis of plasma proteins. Most of plasma proteins are
synthesized in liver: all albumins, 75-90 % of α-globulins, 50 % of β-
globulins, all proteins of blood clotting systems (prothrombin, fibrinogen,
proconvertin, proaccelerine). Only γ-globulins are synthesized in the cells of
reticuloendothelial system.
– synthesis of urea and uric acid;
– synthesis of choline and creatine;
– transamination and deamination of amino acids.
Clinical significance of residual nitrogen measurement in blood. The kinds of
Azotemia - increase of the residual nitrogen content in blood. There are two kinds
of azotemia: absolute and relative.
Absolute azotemia – accumulation of the components of residual nitrogen in
blood. Relative azotemia occurs in dehydration of the organism (diarrhea, vomiting).
Absolute azotemia can be divided on the productive azotemia and retention
azotemia. Retention azotemia is caused by the poor excretion of the nitrogen containing
compounds via the kidneys; in this case the entry of nitrogen containing compounds
into the blood is normal.
Retention azotemia can be divided on the renal and extrarenal. Renal retention
azotemia occurs in kidney diseases (glomerulonephritis, pyelonephritis, kidney
tuberculosis et c.). Extrarenal retention azotemia is caused by the violations of kidney
hemodynamic and decrease of glomerulus filtration processes (heart failure, local
disorders of kidney hemodynamic).
Productive azotemia is conditioned by the enhanced entry of nitrogen containing
compounds into the blood. The function of kidneys in this case doesn’t suffer.

Productive azotemia can be observed in cachexia, leukoses, malignant tumors,
treatment by glucocorticoids.
Prerenal Azotemia
Alternate Names : Azotemia - Prerenal, Renal Underperfusion, Uremia
Azotemia
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Kidney Anatomy
It has been suggested that this article or section be merged into uremia. (Discuss)
Azotemia is a medical condition characterized by abnormal levels of urea,
creatinine, various body waste compounds, and other nitrogen-rich compounds in the
blood as a result of insufficient filtering of the blood by the kidneys.
Uremia can be used as a synonym, or can be used to indicate severe azotemia, in
which symptoms are produced.

Azotemia can be classified according to its cause. In prerenal azotemia the blood
supply to the kidneys is inadequate. In postrenal azotemia the urinary outflow tract is
obstructed. Other forms of azotemia are caused by diseases of the kidneys themselves.
Other causes of azotemia include congestive heart failure, shock, severe burns,
prolonged vomiting or diarrhea, some antiviral medications, liver failure, or trauma to
the kidney(s).
[edit] Signs and symptoms (prerenal azotemia)
position)
Decreased or absent urine output
Fatigue
Decreased alertness
Confusion
Pale skin color
Rapid pulse
Dry mouth
Thirst, swelling (edema, anasarca)
Orthostatic blood pressure (rises or falls, significantly depending on
A urinalysis will typically show a decreased urine sodium level, a high urine
creatinine-to- serum creatinine ratio, a high urine urea-to-serum urea ratio, and
concentrated urine (determined by osmolality and specific gravity). None of these is
particularly useful in diagnosis.
Prompt treatment of some causes of azotemia can result in restoration of kidney
function; delayed treatment may result in permanent loss of renal function. Treatment
may include hemodialysis or peritoneal dialysis, medications to increase cardiac output
and increase blood pressure, and the treatment of the condition that caused the azotemia
to begin with. NOTE: Azotemia is not diagnosed with abnormally high levels of
Creatinine. Azotemia simply refers to an elevated level of urea in the blood.

Added Note: Uremia is not azotemia. Azotemia is one of many clinical
characteristics of uremia, which is a syndome characteristic of renal disease. Uremia
includes Azotemia, as well as acidosis, hyperkalemia, hypertension, anemia and
hypocalcemia along with other findings.
Retrieved from "http://en.wikipedia.org/wiki/Azotemia"
PATIENT HISTORY:
The patient is a 60 year old male with a previous history of thoracic aortic
aneurysm. Currently presents with an abdominal aortic aneurysm and liver and kidney
masses. Admitted for liver and kidney transplant.
The specimen is received unfixed and in three parts.
Part I:
Part 1 is labeled "liver" and consists of a 33.6 pound native hepatectomy, 50.0 x
47.0 x 17.0 cm. The capsular surface is tan and polycystic with cysts ranging from 0.3
to 11.0 cm. in greatest dimension. The capsular surfaces are pink to pink-gray and
occupy approximately 95% of the liver surface. The caudate lobe is 15.0 x 9.0 x 8.0 cm.
and is also almost entirely occupied by cysts. There is no adjacent inferior vena cava.
The associated hepatic veins are pink-gray and free of obstruction. The attached
gallbladder is 21.0 x 3.0 x 2.5 cm. with a pink- gray, smooth serosal surface. The
gallbladder contains approximately 20 cc. of a viscus green bile. It is 6.0 cm. in open

circumference and has a wall thickness of approximately 0.1 cm. The mucosal surface
is trabecular, tan and hemorrhagic. The 1.5 cm. of attached cystic duct is free of
obstruction and 2.0 cm. in open circumference. On dissection of the superficial hilus,
patent portal vein, hepatic arteries and hepatic duct are noted. The cut surface consists
of approximately 5% tan, congested hepatic parenchyma. The remainder consisting of
pink- gray to pink-purple, fluid filled cysts, ranging from 0.3 to 11.0 cm. in greatest
dimension. Some of the larger cysts also contain a gray-green, necrotic material.
Representative tissue is frozen in bulk, submitted for outside research purposes and
stocked in formalin. Gross photographs are taken and sections submitted.
Part II:
Part 2 is labeled "left kidney" and consists of a 1,430 gram native nephrectomy,
24.0 x 11.0 x 9.0 cm. with attached fat and Gerota's fascia. The cortical surface is
almost entirely obliterated by pink-gray and hemorrhagic cysts, ranging from 0.1 to 5.0
cm. in greatest dimension. The kidney has been previously sagittally sectioned,
exposing a cut surface consisting of approximately less than 5% of identifiable renal
cortex at the anterior and posterior aspects. The remainder of the kidney consists of
fluid filled cysts ranging from 0.1 to 5.0 cm. in greatest dimension and pink-white,
grossly unremarkable renal pelvis. Some necrotic, gray-green material is contained
within the larger cyst. The hilar structures consists of patent artery vein and ureter. The
ureter, 8.0 cm. in length, has an irregular pink-gray mucosal surface with some areas
resembling diverticula. Representative tissue is frozen in bulk, submitted in
Karnovsky's fixative for possible electron microscopic evaluation and stocked in
formalin. Gross photos are taken and sections submitted.

Part III:
Part 3 is labeled "spleen" and consists of a 130 gram, purple- gray spleen, 11.0 x
7.0 x 4.0 cm. Torn cauterized capsule is evident at the inferior aspect. A 5.0 x 4.0 x 3.0
cm. bulge is situated at the convexity. On cross section, a 3.0 x 2.0 x 2.0 cm. fluid
filled, multilocular cyst is surrounded by red-brown, splenic parenchyma and patent
malpighian corpuscles. Two separate cysts, 0.3 to 0.6 cm. are adjacent to the main cyst.
No other lesions are noted. The hilus consists of patent vasculature with surrounding
yellow and hemorrhagic fat. Gross photos are taken and representative sections of
spleen with previously mentioned cysts are submitted in cassettes 3A through 3D.
MICROSCOPIC DESCRIPTION
MICROSCOPIC DESCRIPTION:
Factor VIII
Sections from the liver show extensive cyst formation affecting more than 90% of
the liver parenchyma. The limited amount of liver tissue which remains shows a variety
of changes varying from atrophy to hemorrhage. Similar epithelium lined cysts are seen
in the kidney. Some cysts have ruptured and lead to hemorrhagic necrosis, calcification
and fibrosis. Focal cholesterol clefts and foreign body giant cells are seen. The spleen
shows an expanded red pulp and multiple cystic spaces lined by flattened cells.

FINAL DIAGNOSIS
Lipoproteins and Apoproteins
http://www.youtube.com/watch?v=97uiV4RiSAY
Lipids are a group of fatty substances that includes triglycerides (fat), phospholipids and
sterols (e.g. cholesterol). They constitute an important source of energy, serve as precursors for
a number of essential compounds, and are key components of cells and tissues. Cholesterol, for
example, is an indispensable constituent of cellular membranes (1), as well as the precursor for
both steroid hormones and bile acids. On average, the body utilizes approximately 1000
milligrams of cholesterol per day, 30% of which comes directly from foods of animal origin,
and the rest is synthesized in the liver. Due to the insolubility of cholesterol and other fatty
compounds in the blood, their redistribution in the body requires specialized carriers capable of
solubilzing, ferrying, and unloading them at specific target sites. Miscarriage of lipids while in
circulation may lead to atherosclerosis; a clinical condition marked by fatty deposits in the inner
walls of arteries, and the leading cause of death and disability in Western countries.
Most lipids are transported in the blood as part of soluble complexes called lipoproteins
(LPs). Plasma LPs are spherical particles composed of a hydrophobic lipid core surrounded by a
hydrophilic layer, which renders the particles soluble. The lipid core contains primarily
triglycerides (TG) and cholesteryl esters (CE), as well as small amounts of other fatty
compounds, such as sphingolipids and fat-soluble vitamins (e.g. vitamins A, D, E, and K). The
external layer is made of phospholipids, unesterified cholesterol, and specialized proteins, called
apolipoproteins or apoproteins. These proteins facilitate lipid solubilization and help to maintain
the structural integrity of LPs. They also serve as ligands for LP receptors and regulate the
activity of LP metabolic enzymes. As depicted in (Figure 1), the amphipathic molecules that
compose the outer layer of LPs are arranged so that their hydrophobic parts face the central core,
and their hydrophilic regions face the surrounding aqueous environment.

Figure 1: Schematic Illustration of a Lipoprotein Particle
Cholesteryl esters, which do not contain a free hydroxyl group (-OH) are more
hydrophobic than cholesterol, and better accommodated in the core of LPs. The conversion of
cholesterol to CE is catalyzed by a LP-associated enzyme called lecithin-cholesterol
acyltransferase (LCAT). This enzyme, which promotes packaging of cholesteryl molecules in
LPs, is critical for normal cholesterol metabolism. Deficiency of LCAT activity leads to
accumulation of unesterified cholesterol in tissues, and is associated with a number of clinical
conditions including corneal opacity, hemolytic anemia, and premature atherosclerosis.
During ordinary metabolism, plasma LPs lose, acquire, and exchange their lipid and
protein constituents. Normally, fat-rich LPs lose most of their fat within a few hours of food
ingestion, and become smaller and denser particles with higher relative cholesterol content. The
depletion of fat from LPs is catalyzed by lipoprotein lipase (LPL). This lipolytic enzyme is
located on the surface of endothelial capillaries, and degrades triglycerides to free fatty acids
(FFAs) and glycerol. The released FFAs may stay in circulation bound to albumin, or be taken-
up by muscle and fat cells for usage and storage, respectively.
Lipids of dietary origin are processed by intestinal epithelial cells, and then secreted into
the bloodstream as part of large, fat-rich LPs called chylomicrons (chylo = milky, micron=
indicates particle size). En route to the liver, chylomicrons (CM) pass through endothelial
capillaries, lose some fat, and their remnants are taken-up by liver cells. In the liver, the lipids
obtained from CM remnants are re-processed and then secreted back into the bloodstream as

part of very low-density LPs (VLDL). Depletion of fat from VLDL transforms the particle into
an intermediate density lipoprotein (IDL), which upon further degradation of its fat is converted
into a relatively stable particle, called low density lipoprotein (LDL). Because of its high
cholesterol content, LDL is also called LDL-cholesterol. Of the total blood cholesterol, 60-75%
is found in LDL and the rest primarily in high-density lipoprotein (HDL) particles. The main
characteristics of plasma LPs and their associated apoproteins are summarized in (Tables I and
II), respectively.
All peripheral cells express the LDL-receptor (LDLR), and recycle it to the cell surface
upon need for cholesterol. Cholesterol is delivered to these cells through binding of LDL to
LDLR, which triggers endocytosis (internalization) of both species. When the need for
cholesterol is satisfied, the recycling of LDLR is discontinued. Normally, an LDL particle stays
in circulation for no more than a few days before being consumed by a cholesterol needing cell.
However, under conditions of sustained cholesterol excess, the particle stays in circulation for
longer periods of time, and becomes more vulnerable to undesired modifications (e.g.
oxidation). As high levels of oxidized LDL are commonly found in atherosclerotic plaques, they
are thought to be the major inducer of atherosclerotic lesions. Hence, LDL became known as

ad cholesterol. However, today we know that not all LDL particles are bad, and that some LDL
particles, especially very large ones (with diameter >21.3nm), may even provide protection
against atherosclerosis (2). LDL and HDL particle sizes are largely determined by a LP-
associated protein, called CETP (cholesteryl ester transfer protein). This protein enhances
exchange of non-polar lipids, primarily CE and TG, and facilitates tight packaging of CE within
the core of the particles. The end result of prolonged and/or efficient CETP action is smaller
LDL and HDL particles. [The LP-anchored CETP can be envisioned as having a hand that
rotates between the interior and exterior of the particle and capable of holding only one lipid
molecule at a time. Grasping of one molecule releases another and vise versa.]
Genetic variation at the human CETP gene generates proteins with varying degrees of
activity. For example, a single codon variation, from isoleucine to valine at position 405,
generates a mutant protein, designated I405V, which manifests significantly reduced CETP
activity (3, 4). In a new observational study, Barzilai, N. et al. (2) found that people with
homozygosity for the I405V allele have larger HDL and LDL particles, and that this genotype is
associated with exceptional longevity and a markedly reduced risk of coronary artery disease
(CAD). Of the 213 centenarians enrolled in the study, 80% had a high proportion of large LDL
particles, compared to just 8% of the subjects in the control group (256 people in their 60’s and
70’s) (2). Interestingly, HDL and LDL particle sizes are significantly larger in women than in
men, which may account, at least in part, for the longer life expectancies of women.
Unlike LDL, HDL is not recognized by LDLR, and cannot deliver cholesterol to tissue
cells. Instead, it has the ability to remove excess peripheral cholesterol and return it to the liver
for recycling and excretion. This process, called reverse cholesterol transport, is thought to
protect against atherosclerosis. Observational studies over the last 2 decades have consistently
shown strong correlation between elevated HDL levels and low incidents of coronary heart
disease (CHD). Hence HDL has been dubbed ―good‖ cholesterol.
HDL is synthesized in the liver and intestine as a nascent, discoid-shaped particle that
contains predominantly apoA-I, and some phospholipids. Upon maturation, HDL assumes a
spherical shape, and the composition of its core lipids becomes very similar to that of LDL.
However, the relative higher protein content in HDL renders the particle denser and more
resistant to undesired modifications. Unlike the case of LDL, the clearance of HDL from
circulation is not negatively affected by excess cholesterol, which may be another reason why

HDL, despite being much smaller particle than LDL (10nm versus 20nm), is not found in
atherosclerotic plaques. It’s worth noting, that the potential of LPs to become harmful is also
influenced by the character of their lipid constituents. For example, vitamin E and lipids
containing omega-3 fatty acid moieties appear to protect the particles from harmful oxidation
and from getting stuck on the walls of blood vessels.
The functional difference between LDL and HDL results primarily from the different
character of their major apoproteins, apoB-100 and apoA-I, respectively. ApoB-100, which is
found in VLDL, IDL, and LDL, but not in HDL, serves as a ligand for LDLR, and provides
LDL with the means to deliver cholesterol to tissue cells. On the other hand, apoA-I, which is
found exclusively in HDL, has a unique ability to capture and solubilze free cholesterol. This
apoA-I ability enables HDL to act as a cholesterol scavenger.
A mutant apoA-I protein, called apoA-I Milano (apoA-Im), has been identified in a group
of people that live in a small village in northern Italy (5). Carriers of this protein, all
heterozygous for the mutation, had very low levels of HDL (7-14 mg/dl) but showed no clinical
signs of atherosclerosis (5-7). HDL particles in these subjects were markedly larger than control
(12nm versus 9.4nm), which may account for their immunity against premature atherosclerosis.
ApoA-Im differs from natural apoA-I by having a cysteine residue at position 173 instead of
arginine. This cysteine residue forms disulfide bridges with other apoA-I molecules or with
apoA-II (6, 7), which apparently lead to larger HDL particles. It also renders apoA-I more
susceptible to catabolism (8), accounting for the low HDL levels in apoA-Im carriers.
The therapeutic potential of apoA-I has been recently assessed in patients with acute
coronary syndromes (9). Of the 47 patients that participated in a randomized controlled trial, 36
received 5 weekly infusions of recombinant apoA-Im/phospholipid complexes, and 11 received
only saline infusions. The results showed significant regression in coronary atherosclerotic
volume in the apoA-Im treated group, and virtually no change in the control group (9). These
results, if reproduced in larger clinical trials, may constitute a revolutionary breakthrough in the
non-invasive treatment of cardiovascular disease. They should also encourage further
exploration into the therapeutic usefulness of apoA-Im and normal apoA-I in managing
atherosclerotic vascular diseases.
What are lipoproteins?
e LDL (low density lipoproteins) and HDL (high density lipoproteins).

Lipid Levels
The lilipoproteins - Any of the series of soluble lipid-protein complexes which are
transported in the blood; each aggregate particle consists of a spherical hydrophobic
core containing triglycerides and cholesterol esters surrounded by an amphipathic
monolayer of phopholipids, cholesterol and apolipoproteins; classes of lipoproteins
include chylomicrons, very low-density lipoproteins (VLDL), intermediate-density
lipoproteins (IDL), low-density lipoproteins (LDL), and high-density lipoproteins
(HDL).
chylomicrons - The class of largest diameter soluble lipid-protein complexes
which the lowest in density (mass to volume ratio); their composition is ~2%
apolipoproteins, ~5% cholesterol, and ~93% triglycerides and phospholipids; their
normal role is to be synthesized by the intestinal mucosal cells to transport dietary
(exogenous) triglycerides and other lipids from the intestines via the lacteals and
lymphatic system to the systemic circulation to the adipose tissue and liver for storage
and use; they are only present in the blood in significant quantities after the digestion of
a meal.
low-density lipoproteins (LDL) - The class of large diameter soluble lipid-protein
complexes which the fourth lowest in density (mass to volume ratio); their composition
is ~25% apolipoproteins, ~45% cholesterol, and ~30% triglycerides and phospholipids;

their normal role is to transport cholesterol and other lipids from the liver and intestines
to the tissues for use; elevated levels of LDL are associated with increased risk of
cardiovascular disease. nickname - bad cholesterol
high-density lipoproteins (HDL) - The class of small diameter soluble lipid-
protein complexes which the highest in density (mass to volume ratio); their
composition is ~45% apolipoproteins, ~25% cholesterol, and ~30% triglycerides and
phospholipids; their normal role is to transport cholesterol and other lipids from the
tissues to the liver for disposal; elevated levels of HDL are associated with decreased
risk of cardiovascular disease.
very low-density lipoproteins (VLDL) - The class of very large diameter soluble
lipid-protein complexes which the second lowest in density (mass to volume ratio);
their composition is ~10% apolipoproteins, ~40% cholesterol, and ~50% triglycerides
and phospholipids; their normal role is to transport triglycerides and other lipids from
the liver and intestines to the tissues for use; elevated levels of VLDL are associated
with some increased risk of cardiovascular disease.
formation of lipoproteins

http://www.youtube.com/watch?v=97uiV4RiSAY
What is Cholesterol?
Cholesterol is a waxy fat found in the body and, despite what you may have been
told, is a necessary nutrient for the body. Cholesterol is used in the formation of cell
membranes and plays an important role in hormone, bile and vitamin D production.
Cholesterol comes from two sources: the foods that we eat, such as meat, dairy products
and eggs, and our own liver, which produces about eighty percent of all the cholesterol
in the body. That means that only about twenty percent of our total cholesterol is
obtained from food. Since cholesterol is not water-soluble, the liver packages the
cholesterol into tiny spheres called lipoproteins so that the cholesterol can be

transported through the blood. The lipoproteins can be divided into two different
categories: low density and high density lipoproteins.
http://www.youtube.com/watch?v=-WhADd1GKtA&feature=relmfu
Low density lipoprotein (LDL): LDL, often dubbed the "bad" cholesterol, carries
most of the cholesterol in the blood and seems to play a role in the deposition of fat in
arteries. These deposits result in blockages called plaque. In addition to narrowing the
arteries and increasing blood pressure, plaque contributes to the hardening of artery
walls, a condition known as atherosclerosis.
High density lipoprotein (HDL): HDL is known as the "good" cholesterol. HDL
carries cholesterol from the blood back to the liver for elimination. It is also responsible
for removing the plaque buildup along the artery walls. Elevated levels of HDL are very
desirable because it helps to clear blockages in the arteries, reduces LDL and decreases
blood pressure.
What are Triglycerides?
Triglycerides are lipids normally found in increased levels in the blood following
the digestion of fats in the intestine. Consumed calories that are not immediately used
are stored in fat cells in the form of triglycerides and are later released from fatty tissues
when the body needs energy between meals. The major transporter of triglycerides is a
forerunner of LDL, a simpler molecule known as VLDL (very low density lipoprotein).
As the VLDL loses triglycerides, the VLDL particle is converted into intermediate and
then low density lipoprotein. Over time, elevated triglyceride levels may result in

pancreatitis—a condition that can cause malabsorption of nutrients and lead to diabetes.
As pancreatitis progresses, damage can spread to other organs, including the heart,
lungs and kidneys. High triglyceride levels also promote the deposition of cholesterol in
the arteries and are associated with known risk factors for heart disease. The exact role
that triglycerides play as an independent risk factor is not yet clear because people with
high LDL and low HDL levels also have high triglyceride levels.
Although These Researchers Beg to Differ…
One study by Koren-Morag, Graff and Goldbourt, published in the American
Heart Association journal Circulation, found that individuals with elevated triglyceride
levels have a nearly thirty percent increased probability of suffering a stroke, even after
taking into account other risk factors such as cholesterol levels. One of the most
important aspects of the study is that it clarifies the independent link of triglyceride
levels to stroke, meaning that a causal relationship is likely.
What is Plaque?
Excess LDL cholesterol clings to arterial walls as it is transported through the
system. Macrophages eat the LDL and become "foam cells." The cells eventually
rupture and begin to form a lipid layer called plaque. Connective fibers form in and
around the fatty layer, causing it to harden. Over time, the fibrous layer thickens,
narrowing the arterial pathway. When calcium deposits form a crust, the plaque
becomes brittle and is more likely to rupture.

The Problem With Plaque
High blood cholesterol levels increase the likelihood that the fat will be deposited
as plaque on the inner surface of arterial walls. As these deposits increase, the channel
of the artery narrows, contributing to an increase in blood pressure. To compensate, the
heart must work harder to pump the same volume of blood through the narrower
arteries. When the coronary arteries themselves are affected by plaque, the harder
working heart receives less oxygen, thus increasing the risk of heart attack. Plaque also
contributes to hardening of the arteries, or atherosclerosis. This loss of flexibility in
arterial walls elevates blood pressure, putting the heart at additional risk. When the
plaque deposits become unstable, they burst, releasing their cholesterol into the
bloodstream all at once. This can trigger clotting in small coronary arteries. When the
artery is completely obstructed, blood flow stops and a heart attack occurs.
http://www.youtube.com/watch?v=XLLBlBiboJI&feature=related
http://www.youtube.com/watch?v=-WhADd1GKtA&feature=relmfu
What is a Lipoprotein?
Lipids, such as triacylglycerols and cholesterol esters, are virtually insoluble in
aqueous solution. Therefore, lipids must be transported by the circulation in
COMPLEX WITH water-soluble PROTEINS.
This complex LIPOPROTEIN is a globular micelle-like particle that consists of a
nonpolar core of triacylglycerols and cholesterol esters surrounded by an amphiphilic
coating of protein, phospholipid, and cholesterol.
Here is a diagram of Low-Density Lipoprotein (LDL) which is approximately
25nm in diameter:
http://www.youtube.com/watch?v=x-4ZQaiZry8

motion:
ristic
(g/cm)
You need "Quick Time" Player and Plug-In to view this LDL particle in
video
http://www.youtube.com/watch?v=97uiV4RiSAY
Characteristics of Lipoproteins in Human Plasma
Characte
Density
Particle
Diameter (nm)
Particle
Mass (kD)
Chylomicrons VLDL IDL
~0.95 ~1.006
75-1200 30-80
400,000
80,000
10,000-
%Protein a 1.5-2.5 5-10
1.00
6-1.019
35
25-
500
0-10,000
20
15-
DL
.019
-
1.06
3
8-25
300
0-25
L
1
1
2
2
HDL
1.063-1.210
5-12
175-360
40-55
%Phosph 7-9 15-20 22 1 20-35

olipids a 5-20
%Free
Cholesterol a
%Triacyl
glycerols b
%Cholest
eryl Esters b
Major
Apolipoprotein
s
1-3 5-10 8
84-89 50-65 22
3-5 10-15 30
AI,AII,B48,CI
,CII,CIII,E
a Surface Components
b Core Lipids
VLDLy Found in Egg Yolk
B100,CI,
CII,CIII,E
B10
0,CIII,E
-10
-10
5-40
100
7
7
3
B
3-4
3-5
12
AI,AII,CI,CI
I,CIII,D,E
"VLDLy" was coined to signify specific lipoproteins that selectively deposit
triacylglycerol to yolk follicles.
The average size of a VLDLy particle is 30nm, whereas a generic VLDL particle
is approximately 70nm.

VLDLy Metabolism
Theoretically, a 17g egg yolk that contains 2.8g of protein would contain 1.4g of
apoB (49% total yolk protein, MW = 5.5 x 10 5 ). Because VLDLy contains only one
apoB protein per particle, this single egg yolk would contain 1.5 x 10 18 VLDLy

particles. The hen would be producing VLDLy particles at a rate of 1.5 x 10 14 particles
per minute for seven days!!
Biochemistry of immune processes.
http://www.youtube.com/watch?v=Ys_V6FcYD5I&feature=related
Viruses, bacteria, fungi, and parasites that enter the body of vertebrates of are
recognized and attacked by the immune system. Endogenous cells that have
undergone alterations— e. g., tumor cells—are also usually recognized as foreign
and destroyed. The immune system is supported by physiological changes in
infected tissue, known as inflammation. This reaction makes it easier for the
immune cells to reach the site of infection. Two different systems are involved in the
immune response. The innate immune system is based on receptors that can
distinguish between bacterial and viral surface structures or foreign proteins (known
as antigens) and those that are endogenous. With the help of these receptors,
phagocytes bind to the pathogens, absorb them by endocytosis, and break them
down. The complement system (see p. 298) is also part of the innate system. The
acquired (adaptive) immune system is based on the ability of the lymphocytes to
form highly specific antigen receptors ―on suspicion,‖ without ever having met the
corresponding antigen. In humans, there are several billion different lymphocytes,
each of which carries a different antigen receptor. If this type of receptor recognizes
―its‖ cognate antigen, the lymphocyte carrying it is activated and then plays its
special role in the immune response. In addition, a distinction is made between
cellular and humoral immune responses.
The T lymphocytes (T cells) are responsible for cellular immunity. They are
named after the thymus, in which the decisive steps in their differentiation take
place. Depending on their function, another distinction is made between cytotoxic T
cells (green) and helper T cells (blue).

http://www.youtube.com/watch?v=14koX2tbRzU&feature=related
http://www.youtube.com/watch?v=VOD5tuQ5wvo&feature=related
Humoral immunity is based on the activity of the B lymphocytes (B cells, light
brown), which mature in the bone marrow. After activation by T cells, B cells are able
to release soluble forms of their specific antigen receptors, known as antibodies (see p.
300), into the blood plasma. The immune system’s ―memory‖ is represented by
memory cells. These are particularly long–lived cells that can arise from any of the
lymphocyte types described. Simplified diagram of the immune response.
Pathogens that have entered the body—e. g., viruses (top)—are taken up by
antigen-presenting cells (APCs) and proteolytically degraded (1). The viral fragments
produced in this way are then presented on the surfaces of these cells with the help of
special membrane proteins (MHC proteins; see p. 296) (2). The APCs include B
lymphocytes, macrophages, and dendritic cells such as the skin’s Langerhans cells. The
complexes of MHC proteins and viral fragments displayed on the APCs are recognized
by T cells that carry a receptor that matches the antigen (―T-cell receptors‖) (3).
Binding leads to activation of the T cell concerned and selective replication of it (4,
―clonal selection‖).

The proliferation of immune cells is stimulated by interleukins (IL). These are a
group of more than 20 signaling substances belonging to the cytokine family (see p.
392), with the help of which immune cells communicate with each other. For example,
activated macrophages release IL-1 (5), while T cells stimulate their own replication
and that of other immune cells by releasing IL-2 (6). Depending on their type, activated
T cells have different functions. Cytotoxic T cells (green) are able to recognize and
bind virusinfected body cells or tumor cells (7). They then drive the infected cells into
apoptosis (see p. 396) or kill them with perforin, a protein that perforates the target
cell’s plasma membrane (8). B lymphocytes, which as APCs present viral fragments on

their surfaces, are recognized by helper T cells (blue) or their T cell receptors (9).
Stimulated by interleukins, selective clonal replication then takes place of B cells that
carry antigen receptors matching those of the pathogen (10). Thesemature into plasma
cells (11) and finally secrete large amounts of soluble antibodies (12).
• Antigen receptors
Many antigen receptors belong to the immunoglobulin superfamily. The
common characteristic of these proteins is that they aremade up from ―immunoglobulin
domains.‖ These are characteristically folded substructures consisting of 70–110 amino
acids, which are also found in soluble immunoglobulins (Ig; see p. 300). The
illustration shows schematically a few of the important proteins in the Ig superfamily.
They consist of constant regions (brown or green) and variable regions (orange).
Homologous domains are shown in the same colors in each case. All of the receptors
have transmembrane helices at the C terminus, which anchor them to the membranes.
Intramolecular and intermolecular disulfide bonds are also usually found in proteins
belonging to the Ig family. Immunoglobulin M (IgM), a membrane protein on the
surface of B lymphocytes, serves to bind free antigens to the B cells. By contrast, T cell
receptors only bind antigens when they are presented by another cell as a complex with
an MHC protein (see below). Interaction between MHC-bound antigens and T cell
receptors is supported by co-receptors. This group includes CD8, a membrane protein
that is typical in cytotoxic T cells. T helper cells use CD4 as a co-receptor instead (not
shown). The abbreviation ―CD‖ stands for ―cluster of differentiation.‖ It is the term for
a large group of proteins that are all located on the cell surface and can therefore be
identified by antibodies. In addition to CD4 and CD8, there are many other co-receptors
on immune cells
The MHC proteins are named after the ―major histocompatibility complex‖—
the DNA segment that codes for them. Human MHC proteins are also known as
HLA antigens (―human leukocyte-associated‖ antigens). Their polymorphism is so
large that it is unlikely that any two individuals carry the same set of MHC
proteins—except formonozygotic twins. Class I MHC proteins occur in almost all

nucleated cells. They mainly interact with cytotoxic T cells and are the reason for
the rejection of transplanted organs. Class I MHC proteins are heterodimers (áâ).
The â subunit is also known as â2-microglobulin. Class II MHC proteins also
consist of two peptide chains, which are related to each other. MHC II molecules are
found on all antigen- presenting cells in the immune system. They serve for
interaction
T-cell activation The illustration shows an interaction between a virus-infected
body cell (bottom) and a CD8- carrying cytotoxic T lymphocyte (top). The infected cell
breaks down viral proteins in its cytoplasm (1) and transports the peptide fragments into
the endoplasmic reticulum with the help of a special transporter (TAP) (2). Newly
synthesized class I MHC proteins on the endoplasmic reticulum are loaded with one of
the peptides (3) and then transferred to the cell surface by vesicular transport (4). The
viral peptides are bound on the surface of the á2 domain of the MHC protein in a
depression formed by an insertion as a ―floor‖ and two helices as ―walls‖ (see smaller
illustration). Supported by CD8 and other co-receptors, a T cell with a matching T cell

eceptor binds to the MHC peptide complex (5). This binding activates protein kinases
in the interior of the T cell, which trigger a chain of additional reactions (signal
transduction). Finally, destruction of the virus-infected cell by the cytotoxic T
lymphocytes takes place.
Complement system
The complement system is part of the innate immune system (see p. 294). It
supports nonspecific defense against microorganisms. The system consists of some 30
different proteins, the ―complement factors,‖ which are found in the blood and represent
about 4% of all plasma proteins there. When inflammatory reactions occur, the
complement factors enter the infected tissue and take effect there. The complement
system works in three different ways: Chemotaxis. Various complement factors attract
immune cells that can attack and phagocytose pathogens. Opsonization. Certain
complement factors (―opsonins‖) bind to the pathogens and thereby mark them as
targets for phagocytosing cells (e. g., macrophages). Membrane attack. Other
complement factors are deposited in the bacterial membrane, where they create pores
that lyse the pathogen (see below).

• The reactions that take place in the complement system can be initiated in
several ways. During the early phase of infection, lipopolysaccharides and other
structures on the surface of the pathogens trigger the alternative pathway (right).
If antibodies against the pathogens become available later, the antigen– antibody
complexes formed activate the classic pathway (left). Acute-phase proteins are
also able to start the complement cascade (lectin pathway). Factors C1 to C4
(for ―complement‖) belong to the classic pathway, while factors B and D form
the reactive components of the alternative pathway. Factors C5 to C9 are
responsible for membrane attack. Other components not shown here regulate the
system. As in blood coagulation (see p. 290), the early components in the
complement system are serine proteinases, which mutually activate each other
through limited proteolysis. They create a self-reinforcing enzyme cascade.

Factor C3, the products of which are involved in several functions, is central to the
complement system. The classic pathway is triggered by the formation of factor C1 at
IgG or IgM on the surface of microorganisms (left). C1 is an 18-part molecular
complex with three different components (C1q, C1r, and C1s). C1q is shaped like a
bunch of tulips, the ―flowers‖ of which bind to the Fc region of antibodies (left). This
activates C1r, a serine proteinase that initiates the cascade of the classic pathway. First,
C4 is proteolytically activated into C4b, which in turn cleaves C2 into C2a and C2b.
C4B and C2a together form C3 convertase [1], which finally catalyzes the cleavage of
C3 into C3a and C3b. Small amounts of C3b also arise from non-enzymatic hydrolysis
of C3.
The classic pathway is triggered by the formation of factor C1 at IgG or IgM on
the surface of microorganisms (left). C1 is an 18-part molecular complex with three
different components (C1q, C1r, and C1s). C1q is shaped like a bunch of tulips, the
―flowers‖ of which bind to the Fc region of antibodies (left). This activates C1r, a serine
proteinase that initiates the cascade of the classic pathway. First, C4 is proteolytically
activated into C4b, which in turn cleaves C2 into C2a and C2b. C4B and C2a together
form C3 convertase [1], which finally catalyzes the cleavage of C3 into C3a and C3b.
Small amounts of C3b also arise from non-enzymatic hydrolysis of C3. The alternative
pathway starts with the binding of factors C3b and B to bacterial lipopolysaccharides
(endotoxins). The formation of this complex allows cleavage of B by factor D, giving
rise to a second form of C3 convertase (C3bBb). Proteolytic cleavage of factor C3
provides two components with different effects. The reaction exposes a highly reactive

thioester group in C3b, which reacts with hydroxyl or amino groups. This allows C3b to
bind covalently to molecules on the bacterial surface (opsonization, right). In addition,
C3b initiates a chain of reactions leading to the formation of the membrane attack
complex Together with C4a and C5a (see below), the smaller product C3a promotes the
inflammatory reaction and has chemotactic effects. The ―late‖ factors C5 to C9 are
responsible for the development of the membrane attack complex (bottom). They
create an ion-permeable pore in the bacterial membrane, which leads to lysis of the
pathogen. This reaction is triggered by C5 convertase [2]. Depending on the type of
complement activation, this enzyme has the structure C4b2a3b or C3bBb3b, and it
cleaves C5 into C5a and C5b. The complex of C5b and C6 allows deposition of C7 in
the bacterial membrane. C8 and numerous C9 molecules—which form the actual
pore—then bind to this core. Antibodies
http://www.youtube.com/watch?v=lrYlZJiuf18
http://www.youtube.com/watch?v=Ys_V6FcYD5I&feature=related
• Soluble antigen receptors, which are formed by activated B cells (plasma
cells; see p. 294) and released into the blood, are known as antibodies. They are

also members of the immunoglobulin family (Ig; see p. 296). Antibodies are an
important part of the humoral immune defense system. They have no
antimicrobial properties themselves, but support the cellular immune system in
various ways: 1. They bind to antigens on the surface of pathogens and thereby
prevent them from interacting with body cells (neutralization; see p. 404, for
example). 2. They link single-celled pathogens into aggregates (immune
complexes), which are more easily taken up by phagocytes (agglutination). 3.
They activate the complement system (see p. 298) and thereby promote the innate
immune defense system (opsonization). In addition, antibodies have become
indispensable aids in medical and biological diagnosis. Domain structure of
immunoglobulin G _
Type G immunoglobulins (IgG) are quantitatively the most important antibodies
in the blood,where they form the fraction of ã-globulins (see p. 276). IgGs (mass 150
kDa) are tetramers with two heavy chains (H chains; red or orange) and two light
chains (L chains; yellow). Both H chains are glycosylated (violet; see also p. 43). The
proteinase papain cleaves IgG into two Fab fragments and one Fc fragment. The Fab
(―antigen-binding‖) fragments, which each consist of one L chain and the N-terminal
part of an H chain, are able to bind antigens. The Fc (―crystallizable‖) fragment is made
up of the C-terminal halves of the two H chains. This segment serves to bind IgG to cell
surfaces, for interaction with the complement system and antibody transport.
Immunoglobulins are constructed in a modular fashion from several immunoglobulin
domains (shown in the diagram on the right in Ω form). Classes of immunoglobulins
_
http://www.youtube.com/watch?v=mUXIK5gGD1k
Human immunoglobulins are divided into five classes. IgA (with two subgroups),
IgD, IgE, IgG (with four subgroups), and IgM are defined by their H chains, which are
designated by the Greek letters á, ä, å, ã, and µ. By contrast, there are only two types of

L chain (ê and ë). IgD and IgE (like IgG) are tetramers with the structure H2L2. By
contrast, soluble IgA and IgM are multimers that are held together by disulfide bonds
and additional J peptides (joining peptides). The antibodies have different tasks. IgMs
are the first immunoglobulins formed after contact with a foreign antigen. Their early
forms are located on the surface of B cells (see p. 296), while the later forms are
secreted from plasma cells as pentamers. Their action targets microorganisms in
particular. Quantitatively, IgGs are the most important immunoglobulins (see the table
showing serum concentrations). They occur in the blood and interstitial fluid. As they
can pass the placenta with the help of receptors, they can be transferred from mother to
fetus. IgAs mainly occur in the intestinal tract and in body secretions. IgEs are found in
low concentrations in the blood. As they can trigger degranulation of mast cells (see p.
380), they play an important role in allergic reactions. The function of IgDs is still
unexplained. Their plasma concentration is also very low.
Causes of antibody variety _

There are three reasons for the extremely wide variability of antibodies: 1.
Multiple genes. Various genes are available to code for the variable protein domains.
Only one gene from among these is selected and expressed. 2. Somatic recombination.
The genes are divided into several segments, of which there are various versions.
Various (―untidy‖) combinations of the segments during lymphocyte maturation give
rise to randomly combined new genes (―mosaic genes‖). 3. Somaticmutation. During
differentiation of B cells into plasma cells, the coding genes mutate. In this way, the
―primordial‖ germline genes can become different somatic genes in the individual B
cell clones.
Biosynthesis of a light chain _
We can look at the basic features of the genetic organization and synthesis of
immunoglobulins using the biosynthesis of a mouse ê chain as an example. The gene
segments for this light chain are designated L, V, J, and C. They are located on
chromosome 6 in the germ-line DNA (on chromosome 2 in humans) and are separated
from one another by introns (see p. 242) of different lengths. Some 150 identical L

segments code for the signal peptide (―leader sequence,‖ 17–20 amino acids) for
secretion of the product
The V segments, of which there are 150 different variants, code formost of the
variable domains (95 of the 108 amino acids). L and V segments always occur in
pairs—in tandem, so to speak. By contrast, there are only five variants of the J
segments (joining segments) at most. These code for a peptide with 13 amino acids that
links the variable part of the ê chains to the constant part. A single C segment codes for
the constant part of the light chain (84 amino acids). During the differentiation of B
lymphocytes, individual V/J combinations arise in each B cell. One of the 150 L/V
tandem segments is selected and linked to one of the five J segments.
The immune system is a complex, dynamic, and beautifully orchestrated
mechanism with enormous responsibility. It defends against foreign invasion by
microorganisms, screens out cancer cells, adapts as we grow, and modifies how we
interact with our environment. When it malfunctions, disease, cancer or death can
occur. Although it is not necessary to understand all the intimate details of the immune
system, it is wise to have a basic grasp of its functions. More precisely, we should
understand how to stay healthy.
Training the immune system -- the "J" curve
It appears that the immune system has a training effect, similar to other areas of
physiology (e.g., cardiovascular, muscular). In other words, a balanced training
program of exercise and rest leads to better performance. Studies in the laboratory and
epidemiological observations have shown improved immune function and fewer URIs
in athletes as compared to their couch-potato counterparts. This is especially true in
older athletes and it appears that regular exercise can help attenuate the age related
decline in immune function.
On the other hand, too much exercise can lead to a dramatically increased risk of
URIs. The stress of strenuous exercise transiently suppresses immune function. This
interruption of otherwise vigorous surveillance can provide an "open window" for a

variety of infectious diseases -- notably viral illnesses -- to take hold. This is especially
true following single bouts of excessive exercise. For example, it has been observed
that two-thirds of participants developed URIs shortly after completing an
ultramarathon. Similarly, cumulative overtraining weakens the athlete's immune
system, leading to frequent illness and injury.
The best model that accommodates clinical observations and laboratory
experiments is described by the "J"-curve ( Fig. 1). It is important to note that this curve
is individualized. What is moderate training for some is overtraining for others.
Stress is cumulative
In addition to strenuous exercise, other forms of stress may also transiently
suppress immune function. Since exercise is not the only stress factor, an athlete must
consider a host of other variables. There are job responsibilities, family obligations,
social interactions, financial concerns and other components that shape our lives. The
sum of all of these affects a central axis in the body which ultimately influences
immune function. Some of these (e.g., exercise) are under our direct control, and others
only partially or not at all. Recognizing when excess stress occurs is easier if it just
comes from one source. However, all too often it is the sum of many small, difficult to

ecognize changes that tips the scales and sends the athlete into the whirlpool of
overtraining and immunosuppression. Alone and in isolation these small changes would
be manageable, but combined they can overwhelm. (Fig. 2.)
Recommendations
Currently, the best way to stay healthy is to listen to your body. Recognizing the
early warning signs and adapting the training schedule accordingly can help keep you
healthy. In that light, here are some points to ponder and a few recommendations,
Keep a training log. In addition to recording workouts, keep a fatigue score
(scale 0-5). It is expected that a hard workout will make you tired, so it is more
important to note the cumulative "feel" during the day. Granted, the scale is
individualized and subjective, but this simple tool is very useful. If you notice
that your fatigue is progressively increasing over days or weeks, then it is time to
add more rest.
A properly constructed training program that allows for rest and recovery
will help head off problems before they start. Periodization is a way to achieve
that goal.
Record your resting morning heart rate. A progressive increase may tip you
off that you are exceeding your ability to recover.

Anticipate added stress in advance (e.g. new job) and adjust the workout
schedule correspondingly. A small amount of rest early will prevent a bigger
problem later.
To make sure your anti-oxidant defense system is tuned up, eat five
servings of fruit or vegetables per day. Note: vitamin supplements do not appear
to have the same benefits as fruits and vegetables.
October)
Heed your body's early warning signs,
o Disordered sleep (too much or insomnia)
o Loss of interest in pleasurable activities
o Moodiness or depression
o Excessive muscle soreness
o Poor concentration. Lack of mental energy.
o Altered appetite.
o Frequent injury or illness
o Lack of physical energy
Get an annual influenza vaccine (usually available each year starting in
Because frequent URIs or unrelenting fatigue may be a sign of an
underlying illness, it is recommended that you consult your physician.
The Anatomy of the Immune System
The organs of the immune system are stationed throughout the body. They are
generally referred to as lymphoid organs because they are concerned with the growth,
development, and deployment of lymphocytes, the white cells that are the key
operatives of the immune system. Lymphoid organs include the bone marrow and the
thymus, as well as lymph nodes, spleen, tonsils and adenoids, the appendix, and clumps
of lymphoid tissue in the small intestine known as Peyer's patches. The blood and
lymphatic vessels that carry lymphocytes to and from the other structures can also be
considered lymphoid organs.

Cells destined to become immune cells, like all other blood cells, are produced in
the bone marrow, the soft tissue in the hollow shafts of long bones. The descendants of
some so-called stem cells become lymphocytes, while others develop into a second
major group of immune cells typified by the large, cell-and particle-devouring white
cells known as phagocytes.
The two major classes of lymphocytes are B cells and T cells. B cells complete
their maturation in the bone marrow. T cells, on the other hand, migrate to the thymus,
a multilobed organ that lies high behind the breastbone. There they multiply and mature
into cells capable of producing immune response-that is, they become
immunocompetent. In a process referred to as T cell "education," T cells in the thymus
learn to distinguish self cells from nonself cells; T cells that would react against self
antigens are eliminated.

Upon exiting the bone marrow and thymus, some lymphocytes congregate in
immune organs or lymph nodes. Others-both B and T cells-travel widely and
continuously throughout the body. They use the blood circulation as well as a bodywide
network of lymphatic vessels similar to blood vessels.
Laced along the lymphatic routes-with clusters in the neck, armpits, abdomen, and
groin-are small, bean-shaped lymph nodes. Each lymph node contains specialized
compartments that house platoons of B lymphocytes, T lymphocytes, and other cells
capable of enmeshing antigen and presenting it to T cells. Thus, the lymph node brings
together the several components needed to spark an immune response.
The spleen, too, provides a meeting ground for immune defenses. A fist-sized
organ at the upper left of the abdomen, the spleen contains two main types of tissue: the
red pulp that disposes of worn-out blood cells and the white pulp that contains
lymphoid tissue. Like the lymph nodes, the spleen's lymphoid tissue is subdivided into
compartments that specialize in different kinds of immune cells. Microorganisms
carried by the blood into the red pulp become trapped by the immune cells known as
macrophages. (Although people can live without a spleen, persons whose spleens have
been damaged by trauma or by disease such as sickle cell anemia, are highly susceptible

to infection; surgical removal of the spleen is especially dangerous for young children
and the immunosuppressed.)
Nonencapsulated clusters of lymphoid tissue are found in many parts of the body.
They are common around the mucous membranes lining the respiratory and digestive
tracts-areas that serve as gateways to the body. They include the tonsils and adenoids,
the appendix, and Peyer's patches.
The lymphatic vessels carry lymph, a clear fluid that bathes the body's tissues.
Lymph, along with the many cells and particles it carries-notably lymphocytes,
macrophages, and foreign antigens, drains out of tissues and seeps across the thin walls
of tiny lymphatic vessels. The vessels transport the mix to lymph nodes, where antigens
can be filtered out and presented to immune cells.
Additional lymphocytes reach the lymph nodes (and other immune tissues)
through the bloodstream. Each node is supplied by an artery and a vein; lymphocytes
enter the node by traversing the walls of the very small specialized veins.
All lymphocytes exit lymph nodes in lymph via outgoing lymphatic vessels. Much
as small creeks and streams empty into larger rivers, the lymphatics feed into larger and
larger channels. At the base of the neck, large lymphatic vessels merge into the thoracic
duct, which empties its contents into the bloodstream.

Once in the bloodstream, the lymphocytes and other assorted immune cells are
transported to tissues throughout the body. They patrol everywhere for foreign antigens,
then gradually drift back into the lymphatic vessels, to begin the cycle all over again
Disorders of the Immune System: Allergy
http://www.youtube.com/watch?v=NFTL51FvX4Q&feature=related
The most common types of allergic reactions-hay fever, some kinds of asthma, and
hives-are produced when the immune system response to a false alarm. In a susceptible
person, a normally harmless substance-grass pollen or house dust, for example-is
perceived as a threat and is attacked.
Such allergic reactions are related to the antibody known as immunoglobulin E.
Like other antibodies, each IgE antibody is specific; one reacts against oak pollen,
another against ragweed. The role of IgE in the natural order is not known, although
some scientists suspect that it developed as a defense against infection by parasitic
worms.

The first time an allergy-prone person is exposed to an allergen, he or she makes
large amounts of the corresponding IgE antibody. These IgE molecules attach to the
surfaces of mast cells (in tissue) or basophils (in the circulation). Mast cells are plentiful
in the lungs, skin, tongue, and linings of the nose and intestinal tract.
When an IgE antibody siting on a mast cell or basophil encounters its specific
allergen, the IgE antibody signals the mast cell or basophil to release the powerful
chemicals stored within its granules. These chemicals include histamine, heparin, and
substances that activate blood platelets and attract secondary cells such as eosinophils
and neutrophils. The activated mast cell or basophil also synthesizes new mediators,
including prostaglandins and leukotrienes, on the spot.

It is such chemical mediators that cause the symptoms of allergy, including
wheezing, sneezing, runny eyes and itching. They can also produce anaphylactic shock,
a life-threatening allergic reaction characterized by swelling of body tissues, including
the throat, and a sudden fall in blood pressure.
Autoimmune Diseases
Sometimes the immune system's recognition apparatus breaks down, and the body
begins to manufacture antibodies and T cells directed against the body's own
constituents-cells, cell components, or specific organs. Such antibodies are known as
autoantibodies, and the diseases they produce are called autoimmune diseases. (Not all
autoantibodies are harmful; some types appear to be integral to the immune system's
regulatory scheme.)
Autoimmune reactions contribute to many enigmatic diseases. For instance,
autoantibodies to red blood cells can cause anemia, autoantibodies to pancreas cells
contribute to juvenile diabetes, and autoantibodies to nerve and muscle cells are found
in patients with the chronic muscle weakness known as myasthenia gravis.
Autoantibody known as rheumatoid factor is common in persons with rheumatoid
arthritis.
Persons with systemic lupus erythematosus (SLE), whose symptoms encompass
many systems, have antibodies to many types of cells and cellular components. These
include antibodies directed against substances found in the cell's nucleus-DNA, RNA,
or proteins-which are known as antinuclear antibodies, or ANAs. These antibodies can
cause serious damage when they link up with self antigens to form circulating immune

complexes, which become lodged in body tissue and set off inflammatory reactions
(Immune Complex Diseases).
Autoimmune diseases affect the immune system at several levels. In patients with
SLE, for instance, B cells are hyperactive while suppressor cells are underactive; it is
not clear which defect comes first. Moreover, production of IL-2 is low, while levels of
gamma interferon are high. Patients with rheumatoid arthritis, who have a defective
suppressor T cell system, continue to make antibodies to a common virus, whereas the
response normally shuts down after about a dozen days.
No one knows just what causes an autoimmune disease, but several factors are
likely to be involved. These may include viruses and environmental factors such as
exposure to sunlight, certain chemicals, and some drugs, all of which may damage or
alter body cells so that they are no longer recognizable as self. Sex hormones may be
important, too, since most autoimmune diseases are far more common in women than in
men.
Heredity also appears to play a role. Autoimmune reactions, like many other
immune responses, are influenced by the genes of the MHC. A high proportion of
human patients with autoimmune disease have particular histocompatibility types. For
example, many persons with rheumatoid arthritis display the self marker known as
HLA-DR4.
Many types of therapies are being used to combat autoimmune diseases. These
include corticosteroids, immunosuppressive drugs developed as anticancer agents,
radiation of the lymph nodes, and plasmapheresis, a sort of "blood washing" that
removes diseased cells and harmful molecules from the circulation.
Immune Complex Diseases

Immune complexes are clusters of interlocking antigens and antibodies. Under
normal conditions immune complexes are rapidly removed from the bloodstream by
macrophages in the spleen and Kupffer cells in the liver. In some circumstances,
however, immune complexes continue to circulate. Eventually they become trapped in
the tissues of the kidneys, lung, skin, joints, or blood vessels. Just where they end up
probably depends on the nature of the antigen, the class of antibody-IgG, for instance,
instead of IgM-and the size of the complex. There they set off reactions that lead to
inflammation and tissue damage.
Immune complexes work their damage in many diseases. Sometimes, as is the case
with malaria and viral hepatitis, they reflect persistent low-grade infections. Sometimes
they arise in response to environmental antigens such as the moldy hay that causes the
disease known as farmer's lung. Frequently, immune complexes develop in autoimmune
disease, where the continuous production of autoantibodies overloads the immune
complex removal system.
Immunodeficiency Diseases
Lack of one or more components of the immune system results in
immunodeficiency disorders. These can be inherited, acquired through infection or
other illness, or produced as an inadvertent side effect of certain drug treatments.
People with advanced cancer may experience immune deficiencies as a result of
the disease process or from extensive anticancer therapy. Transient immune

deficiencies can develop in the wake of common viral infections, including influenza,
infectious mononucleosis, and measles. Immune responsiveness can also be depressed
by blood transfusions, surgery malnutrition, and stress.
Some children are born with defects in their immune systems. Those with flaws in
the B cell components are unable to produce antibodies (immunoglobulins). These
conditions, known as agammaglobulinemias or hypogammaglobulinemias, leave the
children vulnerable to infectious organisms; such disorders can be combated with
injections of immunoglobulins.
Other children, whose thymus is either missing or small and abnormal, lack T
cells. The resultant disorders have been treated with thymic transplants.
Very rarely, infants are born lacking all the major immune defenses; this is known
as severe combined immunodeficiency disease (SCID). Some children with SCID have
lived for years in germ-free rooms and "bubbles." A few SCID patients have been
successfully treated with transplants of bone marrow (Bone Marrow Transplants).
The devastating immunodeficiency disorder known as the acquired
immunodeficiency syndrome (AIDS) was first recognized in 1981. Caused by a virus
(the human immunodeficiency virus, or HIV) that destroys T4 cells and that is harbored
in macrophages as well as T4 cells, AIDS is characterized by a variety of unusual
infections and otherwise rare cancers. The AIDS virus also damages tissue of the brain
and spinal cord, producing progressive dementia.

AIDS infections are known as "opportunistic" because they are produced by
commonplace organisms that do not trouble people whose immune systems are healthy,
but which take advantage of the "opportunity" provided by an immune defense in
disarray. The most common infection is an unusual and life-threatening form of
pneumonia caused by a one-celled organism (a Protozoa) called Pneumocystis carinii.
AIDS patients are also susceptible to unusual lymphomas and Kaposi's sarcoma, a rare
cancer that results from the abnormal proliferation of endothelial cells in the blood
vessels.
Some persons infected with the AIDS virus develop a condition known as AIDS-
related complex, or ARC, characterized by fatigue, fever, weight loss, diarrhea, and
swollen lymph glands. Yet other persons who are infected with the AIDS virus
apparently remain well; however, even though they develop no symptoms, they can
transmit the virus to others.
AIDS is a contagious disease, spread by intimate sexual contact, by direct
inoculation of the virus into the bloodstream, or from mother to child during pregnancy.
Most of the AIDS cases in the United States have been found among homosexual and
bisexual men with multiple sex partners, and among intravenous drug abusers. Others
have involved men who received untreated blood products for hemophilia; persons who
received transfusions of inadvertently contaminated blood-primarily before the AIDS
virus was discovered and virtually eliminated from the nation's blood supply with a

screening test; the heterosexual partners of persons with AIDS; and children born to
infected mothers.
There is presently no cure for AIDS, although the antiviral agent zidovuzine
(AZT) appears to hold the virus in check, at least for a time. Many other antiretroviral
drugs are being tested, as are agents to bolster the immune system and agents to prevent
or treat opportunistic infections. Research on vaccines to prevent the spread of AIDS is
also under way.
Cancers of the Immune System
Cells of the immune system, like those of other body systems, can proliferate
uncontrollably; the result is cancer. Leukemias are caused by the proliferation of white
blood cells, or leukocytes. The uncontrolled growth of antibody-producing (plasma)
cells can lead to multiple myeloma. Cancers of the lymphoid organs, known as
lymphomas, include Hodgkin's disease. These disorders can be treated-some of them
very successfully-by drugs and/or irradiation.

The Human Immune Response System
An overview of the system

An overview of the system
The human immune response system recognizes pathogens and acts to remove,
immobilize, or neutralize them. The immune system is antigen-specific (responding to
specific molecules on a pathogen) and has memory (its defense to a pathogen is
encoded for future activation). The immune system relies on several components to
fight an infecting pathogen. T cells are lymphocytes that circulate between the blood,
lymph, and lymphoid organs to trigger a systemic immune response with antigen-
receptors on the T cell membrane. B cells are lymphocytes that activate the primary
immune response when antigens bind to their receptors, causing the B cells to
proliferate. Daughter cells of B cells later differentiate into antibody-releasing plasma
cells. B cells also comprise the immune system's memory (see diagram).
Antibodies, also called immunoglobulins, are divided into five classes by structure
and function, enabling them to recognize a wide spectrum of antigens. Antibody
functions include complement fixation that can lead to antigen-cell lysis (rupture) and
can cause inflammation. Antibodies also generate a neutralization response where
viruses and bacteria are destroyed by phagocytes. Agglutination, or clumping together,
of foreign cells are caused by B cells' promotion of complex cross-linking of antibodies
binding to antigens. These agglutinated cells are phagocytized. B cells are cloned in
massive quantities for a single specific antigen.
Immune response to T. cruzi
The human immune response to T. cruzi infection is inadequate; it provides only a
partial defense at best. The immune system's response at its worst causes the defense

mechanisms to turn on the body it is intended to protect, thus often causing more harm
to the person than does T. cruzi.

As T. cruzi immunizes humans to their own antigens, human antibodies attack
myocardial and neural cells.
Complement in humans does not become activated solely by T. cruzi invasion;
antibodies must be present for complement to bind to a specific T. cruzi antigen. This
allows T. cruzi to have time to infect human tissue. Parasite strain and an individual's
immune competence are prime factors in determining the T. cruzi's pathology of an
individual.
Once infected with T. cruzi, humans acquire partial immunity or resistance to the
severe pathologies of Chagas' disease's acute phase through subsequent infections of T.
cruzi. This guards many individuals who live in highly endemic areas from the acute
symptoms of chagas. Complete removable of the parasite from these individuals would
risk the onset of acute chagas through future infection, which is deadly - especially for
children.
T. cruzi incorporates certain host cell membrane proteins onto its surface thereby
masking its antigenic signal to the immune system's lymphocytes. T. cruzi can also
cleave antibody molecules on its surface thereby escaping the immune response's
detection. T. cruzi frequently invade monocytes, a circulating phagocyte. Intracellular
phagocytosis bring amastigotic T. cruzi into tissue cells where they can proliferate.
Once inside tissue cells, T. cruzi are undetected by immune response. Trypomastigotes
remain in the blood stream for a short period of time so that the T. cruzi-specific
immunoglobulins don't have sufficient time to be activated. T. cruzi employs successful
strategies to escape the remarkably potent immune response system. By masking
themselves or by eluding the response mechanisms, the parasite is able to adapt to
survive and continue the life of the species.
Immune response that damages the human body
Unintentional damage is done to the body's otherwise healthy tissue as the
response system attacks what it recognizes as a trigger for a defensive response but

does not recognize that it is attacking itself. This is what's known as an autoimmune
reaction.
Autoimmune responses are responsible in large part for the destructive symptoms
of Chagas disease. This pathology is referred to as immunopathology. Severe
inflammation occurs around tissue that embody amastigotes as the amastigotes release
themselves from the tissue's dead cells. Among the tissue most often encysted is
myocardial neural plexes. Plexes are networks of nerves that serve a variety of organs
and functions. Digestive system neural plexes are targets as well, namely in the colon
and esophagus. During the acute phase of chagas, B and T cells are incited to produce
antibodies. Since T. cruzi is able to mask its presence in the blood, these antibodies do
not attack T. cruzi but instead go after cell membrane antigenic components called
epitopes, that the body's healthy cells and T. cruzi share. Research is being done to
isolate the epitope and how T. cruzi uses it to elude recognition by the immune system.
Scientists work to find a cure to T. cruzi's infecting the human species. As research
continues into how T. cruzi uses the human body as a host, the disciplines of
parasitology and immunology learn much about how these organisms adapt and thrive
in changing environments. T. cruzi proves to be a formidable opponent in the fight.

Mediated by Macrophages
Mediated by Lymphocytes and mast cells

B-Cells
Identical in all Individuals Depends on Exposure to Pathogens
Fixed by Evolution
Evolving within individuals
Parasites, worms, chemicals, toxins generic viruses, bacteria lipoproteins,
lipocarbohydrates bacterial DNA

Phagocytosis (engulfment)
Activation of Antibodies

CD8 Cells